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Best RAM for OverClock GA-P55-UD6 with i750 CPU

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July 10, 2010 2:57:16 PM

Hi folks,

Can anyone offer advice on buying the best compatible DDR3 memory to overclcok a GA-P55-UD6 Mobo fitted with an i750 cpu?

I'm after 2 x 4gb sticks = 8GB in total.
I dont expect to be able to OC the i750 much over 4Ghz, but would like some headroom for upgrading to a faster P55 i5 / i7 CPU in the future.

I have an enermax 650W PSU fitted to my system.

Any advice would be most welcome.
:bounce: 
Related resources
July 14, 2010 10:30:47 PM

bilbat said:
I just use these in a client machine:
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
and they 'dialed in', no problem, even on a Clarkdale...


Thanks, i will have to try them out.. :bounce: 

PS: Does any one know how to check and confirm that an ATI 5870 card installed in the PCI-e 16 slot is actually working at x16 ?

I had to install a Creative Xi-Fi Titanium Champion sfx card in the pci-e x4 card slot...

So just want to check that the ATI is working at full pace.


Once thats confirmed, i need to read up on the 'over clocking guides' for the Gigabyte GA-P55A-UD6 wth i5 750cpu

Since I uninstalled the 'Smart Quick boost' software, the mobo speed has dropped from 3.8Ghz to 2.75 Ghz :fou: 

I have a watercooled system, so CPU willing, should be able to reach 4Ghz
a b à CPUs
a c 177 V Motherboard
July 15, 2010 2:17:19 AM

Try GPU-Z.0.4.4; it should show you the slot size vs the actual lane count in use...

I'm sorry - I didn't read carefully enough the first time - you had requested 4 gig DIMMs, the ones I pointed out are twos. G.Skill can still 'fill the bill', and I've inquired of a few using them, as my next workstation rebuild will be 24G... Try a look at these; - but - ye gods, they're pricey!

I'd ditch any GB s'ware routes to OCing - I can likely give you a working parameter set that will take less than a half-hour to implement...
July 15, 2010 10:06:56 AM

Many thanks for that.... i think i need all the help i can get, particularly as there are so many options now in the Bios and i5 750 CPUs oc differently

I currently have installed Corsair XMS3 4GB (2x2GB) DDR3 PC3-12800C9 1600MHz Dual Channel Kit (CMX4GX3M2A1600C9), which I believe can be used with a i5 750 cpu to reach 4 Ghz OC (depending on a lucky CPU i guess?)

I have an Enermax 650W psu and Corsair H50 liquid cooling set up for the PSU.
All fitted in a large full height tower with good ventilation

GA-P55-UD6 rev: CPU-Z reads it as rev 11 ( but its printed Rev: 1 on the board)
Bios F10
Intel i5 750
Win 7 x64 bit
Saphire ATI 5870 Toxic
2x 30GB OCZ Vertex SSD in Raid 0
2 x 1 TB Samsung F3 in Raid 0

So any parameters / idiot guide to upping my OC to 4Ghz would be most welcome :p 
a b à CPUs
a c 177 V Motherboard
July 15, 2010 4:17:41 PM

GA-P55-UD6
Intel i5-750 x20mult 2.66GHz .65-1.4V 95W TDP (to 4.0GHz)
Corsair XMS3 4GB (2x2GB) DDR3 PC3-12800C9 1600MHz (CMX4GX3M2A1600C9): 9-9-9-24-2t 1.65v nominal

If you haven't yet done it, start with a BIOS' "Load Optimized Defaults"

Before we start ramping things up, I want to teach you a new skill involving the BIOS: Do the <DEL> at the boot to enter the BIOS;
notice, at the bottom, the <F11> "Save CMOS to BIOS" - hit this, and you should get a menu that will show a number (the count varies by BIOS) of empty 'slots', each of which will store an entire set of BIOS parameters, to be re-loaded from the corresponding <F12> "Load CMOS from BIOS"; this is a wonderful overclocker's feature. What I do with it, is to save my 'baseline' working parameters, so if I change something that 'irritates' the board, and forces a reset of all the parameters to defaults, or, even worse, get so screwed up I need to do a 'clear CMOS', I can get back to my starting point with no effort, and without having to remember 85 separate settings! Another thing it prevents is two hours' troubleshooting, having forgotten a change to a crucial parameter - like, "wait a minute - didn't I have the Trd at seven?!" It's pretty self-explanatory, and I alway urge people to start right away by taking the time to give the 'slots' names that mean something: in two hours, "Try2" and "Try3" will not be very helpful, but "450@+10MCH" and "450@+15MCH" will! Another use is for 'green' settings; overclocks, as a rule, do not 'play well' with green features, such as 'down-clocking' and 'down-volting'; with the storage slots, you can set up one profile, say "Green", with all the settings at 'stock' values, and all the 'green' features enabled; another, say "Balls2Wall" with a full overclock, and all the 'green' stuff turned off... Another neat feature of this 'slot' system is, for most BIOS, the mechanism itself will keep track of which ones have booted successfully, and how many times (up to, I believe, a max of five)!

Now, the next step is the most time consuming - we've got to 'sidestep' XMP's limitations. The only reliable way to get the XMP timings for your RAM is to enable XMP - BUT - enabling XMP 'locks out' most all the other OCing parameter changes. Easy to get around, though. Having done a LoadOpt to set up the main config, the next thing you need to do is enable XMP, <F10> to save, exit, and reboot - and then run a pass of MemTest86+ (instructions for D/Ling and 'prepping' MemTest about the middle of Part IV - "Tweaking and tuning") to verify the the XMP for your DIMMs actually works! Assuming it's successful, go into the BIOS, and on the "Advanced Memory Settings" sub-page of the "MB Intelligent Tweaker(M.I.T.)" page of your BIOS, write down (preferable in a neat, tidy, easy-to-read table - extra points here for neatness!! Actually, neatness doesn't count toward your overclock, but accuracy does - if you make a mistake anywhere, you'll, guaranteed, have the devil's [:lorbat:8] own time finding it!) the "Channel Interleaving" and "Rank Interleaving" settings; then, enter the "Channel A Timing Settings" 'sub-sub-page' (?!), and write down all the settings. If I am correct, it will display two sets of timings - on the left, it will show you the 'LoadOpt's 'Auto' parameters; on the right, labeled either XMP or 'Profile (number?) settings', it will show you the 'fast RAM' parameters - these are the ones you need... As an example, here is a table from a client's machine:

CAS 7
tRCD 8
tRP 7
tRAS 24

tRC 40
tRRD 5
tWTR 6
tWR 12
tWTP 23
tWL 7
tRFC 88
tRTP 6
tFAW 50
tCMD 2
static tRD 15

Next, 'back out', and go to the " Channel A Turnaround Settings" 'sub-sub-page' (?if they get many more 'layers' of menuing, I'm gonna lose it!), and scribble those down as well. Now back out again, and look at both sets of 'channel B's' - they should be the same - just double check, and note anything differing...

On to the 'quick' part! First, disable XMP. Then, while you're still 'familiar' with those memory pages, go back and set all of 'em - to the values you wrote down - and don't forget to check the two on the 'main page', "Channel Interleaving" and "Rank Interleaving"... To set these, start with:

"Performance Enhance" to "Standard"
"DRAM Timing Selectable (SPD)" to "Expert"...

At this point, I usually do an <F11> save to BIOS, just so I can easily 'get back to where I was', calling it something like "RAMisSet"...


On the "Advanced Frequency Settings" sub-page:

"CPU Clock Ratio" should already be at "X20"
"CPU Frequency" - this one can't be set, it's calculated

On the "Advanced CPU Core Features" sub-sub-page (there we go again![:fixitbil:9] ):

"Intel(R) Turbo Boost Tech." to "Disabled" (methinks it unreasonable to expect the thing to turbo - your 750 has a helluva 'step' to turbo - goes from x20 to x24, if I'm reading the Intel docs right, and as far as we're gonna 'crank up' the Bclk, even 'under water', 4.8GHz in turbo is just looney!)
"CPU Enhanced Halt (C1E)" to "Disabled"
"C3/C6/C7 State Support" to "Disabled"
"CPU Thermal Monitor" to "Enabled
"CPU EIST Function" to "Disabled"
"Bi-Directional PROCHOT" to "Enabled
"Virtualization Technology" to "Enabled, if you intend to use it - it has costs...

'Back out', to the "Advanced Frequency Settings" sub-page again:

The next one, I really don't know what the hell is going on! The i5-750 doesn't do QPI, and neither did the last 650 I did, but the damned BIOS shows it! I thought, perhaps, the setting 'doubled' as a DMI setting, but the parameters I got were way too high to be DMI?!? Anyway, reduce whatever muliplier is shown here to about two-thirds the original value, or set it as low as it goes, if 'two-thirds' is lower than the available settings - this is on my list of 'items to dig into'!!

"Uncore Clock Ratio" should be 'fixed' at X20

...under " Standard Clock Control":

"Base Clock(BCLK) Control" to "Enabled"
"BCLK Frequency(Mhz)" to "200"
"System Memory Multiplier" to "X8"
"Memory Frequency" - once again, this one can't be set, it's calculated - should read ~1600...
"PCI Express Frequency (Mhz)" to "100" (not auto...)
"C.I.A.2" to "Disabled"


On the "Advanced Voltage Settings" sub-page:

"Load-Line Calibration" is anyone's guess - this seems to work differently on every single board I do - even, sometimes, differing between boards of the same model with different CPUs! My best guess - start with it at "Standard", and, maybe, adjust when 'running thermals'...
"CPU Vcore" to "1.325V" - idea here is to start high, to get 'er stable first, then reduce voltage when 'running thermals' - doing it the other way - starting low, and trying to 'creep up' the Vcore is a real PITA, as, often, if the MOBO's not 'happy' with OC settings, she'll 'crank back' to the LoadOpt parameters - and you lose anything you didn't have the foresight to 'save to BIOS'! (...shouldn't be any worry, between 'water' and the Vid_max on the 750 being 1.4V...)

"QPI/Vtt Voltage" to "1.225V"
"PCH Core" to "1.10V"
"DRAM Voltage" to "1.66V" - 'even' increments only - can't set the rated 1.65 directly...


On the "Advanced BIOS Features" page:

"Quick Boot" to "Disabled"
"Full Screen LOGO Show" to "Disabled" (easier to get into the BIOS + lets you 'see' the POST...)

On the "Integrated Peripherals" page:

...disable everything you're not actually planning on using - no 1394 port - turn it off!; same for serial port, eSATA, etc - if you don't need it, the processor/system doesn't need the 'overhead' either!

On the "Power Management Setup" page:

"ACPI Suspend Type" to "S1(POS)" (S3 is notoriously difficult to get working properly on OC'd boards...)

On the "PC Health Status" page:

"CPU Warning Temperature" to "70C"

And that should do it! Time for, first, an <F11> 'save to BIOS', followed by an <F10> save & exit - hopefully, she'll reboot, and WORK!

I should point out that getting two reboots in a row here is perfectly normal behavior; it seems that, when you change certain settings (and we don't exactly know which ones - the only sure one I know is Trd - if you change it, I think you get the 'twin' reboot) it boots once to 'see where it's at', recalculates its remaining 'auto' settings, saves them, and then boots again. Three reboots in a row, however, usually indicates that the board was 'given indigestion' by your settings, and is going back to defaults. This sometimes goes astray, and it doesn't get back into proper operation - for example, at this point, mine will sometimes 'lock' itself into 111MHz x a six multiplier - and take a week to do a whole boot - that's time to do a CMOS reset, and use your 'stored' <F12> profile to get back to where you were...

Good luck!

Bill [:jaydeejohn:3]
July 16, 2010 11:25:11 AM

bilbat said:
GA-P55-UD6
Intel i5-750 x20mult 2.66GHz .65-1.4V 95W TDP (to 4.0GHz)
Corsair XMS3 4GB (2x2GB) DDR3 PC3-12800C9 1600MHz (CMX4GX3M2A1600C9): 9-9-9-24-2t 1.65v nominal

If you haven't yet done it, start with a BIOS' "Load Optimized Defaults"

Before we start ramping things up, I want to teach you a new skill involving the BIOS: Do the <DEL> at the boot to enter the BIOS;
notice, at the bottom, the <F11> "Save CMOS to BIOS" - hit this, and you should get a menu that will show a number (the count varies by BIOS) of empty 'slots', each of which will store an entire set of BIOS parameters, to be re-loaded from the corresponding <F12> "Load CMOS from BIOS"; this is a wonderful overclocker's feature. What I do with it, is to save my 'baseline' working parameters, so if I change something that 'irritates' the board, and forces a reset of all the parameters to defaults, or, even worse, get so screwed up I need to do a 'clear CMOS', I can get back to my starting point with no effort, and without having to remember 85 separate settings! Another thing it prevents is two hours' troubleshooting, having forgotten a change to a crucial parameter - like, "wait a minute - didn't I have the Trd at seven?!" It's pretty self-explanatory, and I alway urge people to start right away by taking the time to give the 'slots' names that mean something: in two hours, "Try2" and "Try3" will not be very helpful, but "450@+10MCH" and "450@+15MCH" will! Another use is for 'green' settings; overclocks, as a rule, do not 'play well' with green features, such as 'down-clocking' and 'down-volting'; with the storage slots, you can set up one profile, say "Green", with all the settings at 'stock' values, and all the 'green' features enabled; another, say "Balls2Wall" with a full overclock, and all the 'green' stuff turned off... Another neat feature of this 'slot' system is, for most BIOS, the mechanism itself will keep track of which ones have booted successfully, and how many times (up to, I believe, a max of five)!

Now, the next step is the most time consuming - we've got to 'sidestep' XMP's limitations. The only reliable way to get the XMP timings for your RAM is to enable XMP - BUT - enabling XMP 'locks out' most all the other OCing parameter changes. Easy to get around, though. Having done a LoadOpt to set up the main config, the next thing you need to do is enable XMP, <F10> to save, exit, and reboot - and then run a pass of MemTest86+ (instructions for D/Ling and 'prepping' MemTest about the middle of Part IV - "Tweaking and tuning") to verify the the XMP for your DIMMs actually works! Assuming it's successful, go into the BIOS, and on the "Advanced Memory Settings" sub-page of the "MB Intelligent Tweaker(M.I.T.)" page of your BIOS, write down (preferable in a neat, tidy, easy-to-read table - extra points here for neatness!! Actually, neatness doesn't count toward your overclock, but accuracy does - if you make a mistake anywhere, you'll, guaranteed, have the devil's [:lorbat:8] own time finding it!) the "Channel Interleaving" and "Rank Interleaving" settings; then, enter the "Channel A Timing Settings" 'sub-sub-page' (?!), and write down all the settings. If I am correct, it will display two sets of timings - on the left, it will show you the 'LoadOpt's 'Auto' parameters; on the right, labeled either XMP or 'Profile (number?) settings', it will show you the 'fast RAM' parameters - these are the ones you need... As an example, here is a table from a client's machine:

CAS 7
tRCD 8
tRP 7
tRAS 24

tRC 40
tRRD 5
tWTR 6
tWR 12
tWTP 23
tWL 7
tRFC 88
tRTP 6
tFAW 50
tCMD 2
static tRD 15

Next, 'back out', and go to the " Channel A Turnaround Settings" 'sub-sub-page' (?if they get many more 'layers' of menuing, I'm gonna lose it!), and scribble those down as well. Now back out again, and look at both sets of 'channel B's' - they should be the same - just double check, and note anything differing...

On to the 'quick' part! First, disable XMP. Then, while you're still 'familiar' with those memory pages, go back and set all of 'em - to the values you wrote down - and don't forget to check the two on the 'main page', "Channel Interleaving" and "Rank Interleaving"... To set these, start with:

"Performance Enhance" to "Standard"
"DRAM Timing Selectable (SPD)" to "Expert"...

At this point, I usually do an <F11> save to BIOS, just so I can easily 'get back to where I was', calling it something like "RAMisSet"...


On the "Advanced Frequency Settings" sub-page:

"CPU Clock Ratio" should already be at "X20"
"CPU Frequency" - this one can't be set, it's calculated

On the "Advanced CPU Core Features" sub-sub-page (there we go again![:fixitbil:9] ):

"Intel(R) Turbo Boost Tech." to "Disabled" (methinks it unreasonable to expect the thing to turbo - your 750 has a helluva 'step' to turbo - goes from x20 to x24, if I'm reading the Intel docs right, and as far as we're gonna 'crank up' the Bclk, even 'under water', 4.8GHz in turbo is just looney!)
"CPU Enhanced Halt (C1E)" to "Disabled"
"C3/C6/C7 State Support" to "Disabled"
"CPU Thermal Monitor" to "Enabled
"CPU EIST Function" to "Disabled"
"Bi-Directional PROCHOT" to "Enabled
"Virtualization Technology" to "Enabled, if you intend to use it - it has costs...

'Back out', to the "Advanced Frequency Settings" sub-page again:

The next one, I really don't know what the hell is going on! The i5-750 doesn't do QPI, and neither did the last 650 I did, but the damned BIOS shows it! I thought, perhaps, the setting 'doubled' as a DMI setting, but the parameters I got were way too high to be DMI?!? Anyway, reduce whatever muliplier is shown here to about two-thirds the original value, or set it as low as it goes, if 'two-thirds' is lower than the available settings - this is on my list of 'items to dig into'!!

"Uncore Clock Ratio" should be 'fixed' at X20

...under " Standard Clock Control":

"Base Clock(BCLK) Control" to "Enabled"
"BCLK Frequency(Mhz)" to "200"
"System Memory Multiplier" to "X8"
"Memory Frequency" - once again, this one can't be set, it's calculated - should read ~1600...
"PCI Express Frequency (Mhz)" to "100" (not auto...)
"C.I.A.2" to "Disabled"


On the "Advanced Voltage Settings" sub-page:

"Load-Line Calibration" is anyone's guess - this seems to work differently on every single board I do - even, sometimes, differing between boards of the same model with different CPUs! My best guess - start with it at "Standard", and, maybe, adjust when 'running thermals'...
"CPU Vcore" to "1.325V" - idea here is to start high, to get 'er stable first, then reduce voltage when 'running thermals' - doing it the other way - starting low, and trying to 'creep up' the Vcore is a real PITA, as, often, if the MOBO's not 'happy' with OC settings, she'll 'crank back' to the LoadOpt parameters - and you lose anything you didn't have the foresight to 'save to BIOS'! (...shouldn't be any worry, between 'water' and the Vid_max on the 750 being 1.4V...)

"QPI/Vtt Voltage" to "1.225V"
"PCH Core" to "1.10V"
"DRAM Voltage" to "1.66V" - 'even' increments only - can't set the rated 1.65 directly...


On the "Advanced BIOS Features" page:

"Quick Boot" to "Disabled"
"Full Screen LOGO Show" to "Disabled" (easier to get into the BIOS + lets you 'see' the POST...)

On the "Integrated Peripherals" page:

...disable everything you're not actually planning on using - no 1394 port - turn it off!; same for serial port, eSATA, etc - if you don't need it, the processor/system doesn't need the 'overhead' either!

On the "Power Management Setup" page:

"ACPI Suspend Type" to "S1(POS)" (S3 is notoriously difficult to get working properly on OC'd boards...)

On the "PC Health Status" page:

"CPU Warning Temperature" to "70C"

And that should do it! Time for, first, an <F11> 'save to BIOS', followed by an <F10> save & exit - hopefully, she'll reboot, and WORK!

I should point out that getting two reboots in a row here is perfectly normal behavior; it seems that, when you change certain settings (and we don't exactly know which ones - the only sure one I know is Trd - if you change it, I think you get the 'twin' reboot) it boots once to 'see where it's at', recalculates its remaining 'auto' settings, saves them, and then boots again. Three reboots in a row, however, usually indicates that the board was 'given indigestion' by your settings, and is going back to defaults. This sometimes goes astray, and it doesn't get back into proper operation - for example, at this point, mine will sometimes 'lock' itself into 111MHz x a six multiplier - and take a week to do a whole boot - that's time to do a CMOS reset, and use your 'stored' <F12> profile to get back to where you were...

Good luck!

Bill [:jaydeejohn:3]



Many thanks for the adice, I will have to give it ago over the weekend........ at least when my head explodes on the Saturday, i'll have sunday to recover :pt1cable: 
a b à CPUs
a c 177 V Motherboard
July 16, 2010 2:39:56 PM

Ah - don't be too concerned - it takes longer to read it (and infinitely longer to write it :pt1cable:  ) than to do it - easiest thing: copy the whole thing into notepad to get rid of the formatting, print it out, and 'check off' each item as you go...
July 30, 2010 12:12:33 PM

bilbat said:
Ah - don't be too concerned - it takes longer to read it (and infinitely longer to write it :pt1cable:  ) than to do it - easiest thing: copy the whole thing into notepad to get rid of the formatting, print it out, and 'check off' each item as you go...


bilbat said:
Ah - don't be too concerned - it takes longer to read it (and infinitely longer to write it :pt1cable:  ) than to do it - easiest thing: copy the whole thing into notepad to get rid of the formatting, print it out, and 'check off' each item as you go...


bilbat said:
Ah - don't be too concerned - it takes longer to read it (and infinitely longer to write it :pt1cable:  ) than to do it - easiest thing: copy the whole thing into notepad to get rid of the formatting, print it out, and 'check off' each item as you go...


Hi Bilbat,
Sorry for the late reply, but have been away.
Well i had ago at OC using your supplied guide several times, but didnt succeed :pt1cable: 
Was there any settings missed out? regardless what i try the 'uncore clock ratio' is stuck at x16

After carrying out the Mem test for 2 hours (passed ok) i followed your instructions for checking the "Advanced Memory" readings.
The Channel Interleaving figure remains ghosted in blue = -6 Auto
The Rank Interleaving figure remains ghosted in blue = -4 Auto

The Channel A & Channel B Time Settings subpage (both channels had the same readings)
the figures to the left were ghosted blue and the column to the right was ghosted blue with 'auto' against each reading
(there was no ref to fast ram or profile settings)

In the same column 'Static tRD' is not in the submenu (not there)

Channel A & B Misc Timings read as follows

B2B CAS Delay was blank apart from a 'dash' '-' (or Auto) The max decimal setting you could set was 30
Round Trip Latency (A & B) A = 48 B=48

Turnaround Settings A & B
Diff Dimms = 6 & 6
Diff Ranks = 5 & 5
On same Rank = 1 & 1

Writes were
6 & 6
6 & 6
1 & 1

Ref your advanced memory settings..page
XMP was disabled
SPD (was not mentioned!?) - options are auto or 6,8,10. Tried leaving at both auto or set to 8.


Performance enhance = Standard
DRAM Timing Selectable = Expert


For your Advanced Frequency Settings

CPU Clock Ratio = x20
Cpu Frequency = 2.66Ghz (133x20) ghosted blue

For your Advanced CPU Core Settings
I followed your checklist

'Virtualisation Tech' was not there, but in 'Miscellaneous Settings' (set to enable) what do you mean by it has costs?
Also found in Misc was Isochronus support (enabled)

Backout to For your Advanced Frequency Settings
QPI Clock Ratio (Auto) set to x32 (lowest it would go - x32, x36, Auto)

The following were ghosted blue
QPI Linkspeed = 4.26 GHz
Uncore Clock Control = x16 (not 20) - This remains ghosted at x16 regardless what i change
Uncore frequency = 2133 Ghz

under 'standard clock control'

BCLK Control = Enabled
BCLK Frequency = 200
XMP ? = Disabled ? (This was not mentioned in your guide)
Sys Mem Multi = x8
Memory Frequency = ghosted blue 1600
PCI E = 100
CIA2 = Disabled



I followed all the rest of your voltage / bios / power instructions etc to the letter, but no joy, the PC bootpage informs you that an overclock or voltage change has prevented booting.

Any ideas...
July 30, 2010 12:24:11 PM

bilbat said:
Ah - don't be too concerned - it takes longer to read it (and infinitely longer to write it :pt1cable:  ) than to do it - easiest thing: copy the whole thing into notepad to get rid of the formatting, print it out, and 'check off' each item as you go...


I forgot to add.. the mem timings i inputted were


CAS 9
tRCD 9
tRP 9
tRAS 24

tRC 41
tRRD 6
tWTR 6
tWR 12
tWTP 24
tWL 8
tRFC 88

tRTP 6
tFAW 30
tCMD 2
static tRD (This was missing from list)

Channel A & B Misc Timings

B2B Cas Delay = '-' (ghosted in blue) or 'Auto' So left as auto. as didnt no what to set!
Roundtrip latency = 48


a b à CPUs
a c 177 V Motherboard
July 30, 2010 2:14:52 PM

Just woke up - gotta get two or three cups of coffee in me [:isamuelson:6] Only see one thing at first glance:
Quote:
XMP ? = Disabled ? (This was not mentioned in your guide)

Quote:
Now, the next step is the most time consuming - we've got to 'sidestep' XMP's limitations.

On to the 'quick' part! First, disable XMP. Then, while you're still 'familiar' with those memory pages, go back and set all of 'em

Have to have it disabled, once you've read and recorded all the parameters, or half the other stuff is 'locked'...

I've got to pull some Intel docs - it's been my understanding that uncore on all i5's is 'locked' at X20; however, even at X16, a X8 memory multiplier should work - rule is uncore has to be at least twice the memory mult...

In the meantime, what I'd do is test your XMP parameters for your particular RAM. Put two DIMMs in DDR3_1 and DDR3_4; go into the BIOS and do a LoadOpt; <F10> to save, exit, and reboot; enter the BIOS again and enable XMP, once again <F10> to save, exit, and reboot; now, boot to MemTest (comprehensive MemTest instructions are at about the middle of Memory Part IV - "Tweaking and tuning") and let it run a pass or two; then, assuming no errors, reboot and disable XMP, exchange for the other two DIMMs, redo the LoadOpt and XMP enable, and test the other two. What we want here is confirmation that the XMP profiles on your DIMMs will actually work the way they are designed to - at one DIMM per channel...





July 30, 2010 5:32:04 PM


Have to have it disabled, once you've read and recorded all the parameters, or half the other stuff is 'locked'...

I've got to pull some Intel docs - it's been my understanding that uncore on all i5's is 'locked' at X20; however, even at X16, a X8 memory multiplier should work - rule is uncore has to be at least twice the memory mult...

In the meantime, what I'd do is test your XMP parameters for your particular RAM. Put two DIMMs in DDR3_1 and DDR3_4; go into the BIOS and do a LoadOpt; <F10> to save, exit, and reboot; enter the BIOS again and enable XMP, once again <F10> to save, exit, and reboot; now, boot to MemTest (comprehensive MemTest instructions are at about the middle of Memory Part IV - "Tweaking and tuning") and let it run a pass or two; then, assuming no errors, reboot and disable XMP, exchange for the other two DIMMs, redo the LoadOpt and XMP enable, and test the other two. What we want here is confirmation that the XMP profiles on your DIMMs will actually work the way they are designed to - at one DIMM per channel...[/quotemsg]



Yes XMP was disabled after i had ran the memory tests and noted down the memory readings. But what i meant was that XMP (disable option) appears in 2 of the Advanced setting pages, Memory and Frequency pages, not just once. But i turned it off in both any way.

The SPD setting appears on both the Memory and Frequency pages too, so i set that to x8 on both

On the Channel A & B Timing settings page, i inputted the memory readings i had written down earlier, as you said in the guide.
however, the

static tRD was nowhere to be found in that list.

Also in the
Channel A & B Misc Timings

B2B Cas Delay reading was a (dash) '-' (ghosted in blue)in the left column or 'Auto' in the right column. I left it as auto as i didnt know what to set it at.


As to the Dimms, I'm only using 2 x 2 GB dimms in the DDR3 Dual channel slots
These are Corsair XMS3 4GB (2x2GB) DDR3 PC3-12800C9 1600MHz Dual Channel Kit (CMX4GX3M2A1600C9) and have been assured that these will clock an i5 750 & GA-P55-UD6 to 4Ghz+ (as long as the CPU is not a crock)

Using Easy Tune set to turbo, i can get 3.8 Ghz CPU clock in software



a b à CPUs
a c 177 V Motherboard
July 31, 2010 1:26:10 AM

That 'on two pages' thing seems distracting. It should always be the same setting; i.e., if you disable XMP on one of the pages it appears on, going to the other page it's visible on should also be disabled - it just makes things harder to explain... I'm still trying to track down that x16 uncore - haven't a clue yet, and have read several sets of specs - what BIOS rev are you running?

ah - in the interim, finally! "In order to save power, Intel uses slower transistors that have lower leakage for the un-core. As a result, the un-core can't clock up as high as the core and runs at a lower multiplier." Now, to digest the rest of it...
August 1, 2010 11:35:20 PM

bilbat said:
That 'on two pages' thing seems distracting. It should always be the same setting; i.e., if you disable XMP on one of the pages it appears on, going to the other page it's visible on should also be disabled - it just makes things harder to explain... I'm still trying to track down that x16 uncore - haven't a clue yet, and have read several sets of specs - what BIOS rev are you running?

ah - in the interim, finally! "In order to save power, Intel uses slower transistors that have lower leakage for the un-core. As a result, the un-core can't clock up as high as the core and runs at a lower multiplier." Now, to digest the rest of it...



This is the set up i have..

currently have installed Corsair XMS3 4GB (2x2GB) DDR3 PC3-12800C9 1600MHz Dual Channel Kit (CMX4GX3M2A1600C9), which I believe can be used with a i5 750 cpu to reach 4 Ghz OC (depending on a lucky CPU i guess?)

I have an Enermax 650W psu and Corsair H50 liquid cooling set up for the PSU.
All fitted in a large full height tower with good ventilation

GA-P55-UD6 rev: CPU-Z reads it as rev 11 ( but its printed Rev: 1 on the board)
Bios F10
Intel i5 750
Win 7 x64 bit
Saphire ATI 5870 Toxic OC
!