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Question about my current memory configuration

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April 18, 2011 3:54:09 PM

Hello,

I have a gigabyte 890GPA-UD3H and currently have 12 gb of ddr3 corsair vengeance ram. I am confused about my current config and dual channel. It is 3x4gb sticks with 4 total slots. I didn't think this would work as dual channel because of the extra slot being filled. But after reading the memory FAQ on here it says to check CPU-id and look under memory tab at channel # to find out. As it is setup now it does say dual... So I guess my question is can I assume that it is actually working in dual channel mode? I guess it depends on the mobo and what it supports?

Thanks for any input as it's driving me crazy.
a c 347 } Memory
April 18, 2011 4:19:12 PM

No, Dual Channel is not possible with odd number sticks unless you pull the 1 stick. I'm not suggesting that you do, and the advantages of 12GB non-Dual vs 8GB Dual don't justify pulling a 4GB stick.

In order to achieve Dual Channel the size/channel must be equal, so if Dual Channel is active then you'd have 8GB {2X4GB}. Some MOBO can and will deactivate some memory to achieve Dual Channel. Example A > B = B*2 ; A < B = A*2 ; A = B == A + B.

If you have Windows 7 make certain that you're getting ALL 12GB, if the Hardware Reserved is > xxxMB {not GB} then your BIOS turned-off the 4GB odd stick:

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April 18, 2011 4:30:58 PM

I know for sure I have 12xxx mb total of ram (can't remember the last 3 digits). See thats what I thought too. Its just weird because the 3 utilities I use (CPU ID, amd overdrive and everest) all mention dual channel. Either way if it's better to have 12 vs 8 then I'll keep it as is.

Thanks a lot!
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a c 347 } Memory
April 18, 2011 5:03:03 PM

In the example above, 9MB of 6GB is used as Hardware Reserved. If the BIOS turned-off a DIMM slot then I'd have 2057+ MB listed for Hardware Reserved or in other words useless to Windows a/k/a lost. In XP see System Properties - general tab.

Good Luck! :) 
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April 18, 2011 6:07:27 PM

Hey Jaquith,

I checked my resource monitor and it states 3 MB is Hardware reserved, 1940 MB in use, 211 MB Modified, 1433 MB standby, 8705 MB Free, so that means it is not lost to Windows right?
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a c 347 } Memory
April 18, 2011 6:22:32 PM

1940
0211
1433
8705
====
12289 MB = 12GB You're good, all of the RAM is being utilized properly! :) 

Always good to check and have peace of mind.
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April 18, 2011 7:57:07 PM

Right on! So as it stands then I should leave it as is? I am still confused as to why all these utilities are telling me Channel: Dual etc, but regardless of what its running at as long as 12 GB is better than 8 GB overall then I am happy!

The only other thing I am wondering now is why when I tried to switch to 1T command rate with AMD overdrive my comp locked up. It seems corsair said this RAM is good for overclocking, but maybe they are not referring to the timings etc and more just the clock speed?
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a c 347 } Memory
April 18, 2011 8:25:20 PM

The only oddball exception that I know of is called 'Flex Mode' which is an Intel 'thing' which would allow the 2 4GB as 'Dual' Channel and the odd 1 4GB as 'Single' Channel.

Looking at your manual, pg 16, it's pretty clear for Dual Channel you need 'pair' of RAM installed in the color coded banks for the Channels.

edit:
bryanb58 said:
The only other thing I am wondering now is why when I tried to switch to 1T command rate with AMD overdrive my comp locked up. It seems corsair said this RAM is good for overclocking, but maybe they are not referring to the timings etc and more just the clock speed?


Not uncommon, 'most' fast DDR3 has a Command Rate of 2T {a/k/a 2N} and when running Rated Speed RAM 1600 MHz or faster most RAM is 2T. If you're trying to run your RAM faster than Rated Speed then I would either raise the Frequency 1600 -> 1800 MHz and/or lower the CAS 9-9-9 -> 8-8-8, and often this requires either or both an increase of DRAM Voltage and/or QPI/DRAM Voltage {IMC, VTT, NB, etc}. Also, there's no guarantees.

Example:
1600 9-9-9-24-2T @ 1.65v Stock
1800 9-9-9-24-2T @ 1.65v~1.70v OC Frequency
1600 8-8-8-24-2T @ 1.65v~1.70v OC CAS Timings
1800 8-8-8-24-2T @ 1.65v~1.70v OC both
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April 18, 2011 9:20:18 PM

Alright, thanks for the clarification. Actually, my RAM is rated for 1600 Mhz but my Mobo only supports 1333 Mhz which I have it at now, so actually its lower then it should be. so that would make sense why it wouldnt work right now. It actually in the manual also says it supports 2000(OC) but I dont really understand how you would activate that.... Anyways the memory timings and such are a bit overwhelming to me, I think my ram is working good as is, so I should probably just leave it for now.

I am actually actively talking to someone in Overclocking forum on here to start looking at OCing, and I know that the NB and HT and DRAM freqs are all connected, so maybe when I up that and the DRAM freq goes up, does it just mean that I can acheive that 2000 MHz with that Mobo if the RAM can handle it?

Thanks for all the help jaquith
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a c 347 } Memory
April 18, 2011 9:36:03 PM

What CPU? Most Phenom II will run 1600 MHz RAM, I doubt you'll need to increase the CPU Frequency(MHz).

Set Memory Clock -> 8 ; 8 X 200 = 1600 MHz
DRAM Configuration / Enter
Set the CAS timings ; per spec e.g. 9-9-9-24
Set 1T/2T Command Timing - 2T
--
DRAM Voltage Control -> 1.65v ; per spec e.g. 1.65v
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April 18, 2011 10:00:54 PM

It is the phenom II x6 1055t. I was referring to what the MOBO states in the specs for memory speed supports, although now that you mention it when I look in the bios, there is a X8 to bump it to 1600 mhz...So I should probably do that right???

I know that the CAS timings are already 9-9-9-24 and the command timing is at 2T. Does that mean then that I shouldnt need to alter the voltages if the RAM already is rated at 1600 Mhz?

Thanks once again jaquith!
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a c 347 } Memory
April 18, 2011 10:30:09 PM

Yep, do as I suggested above. Auto settings is a bad idea, especially if you OC - my experience is the DRAM Voltage gets too high and XMP info cannot be read by AMD MOBO so more than likely Auto is going to set the CAS timings incorrectly.

Good Luck - let me know! :) 

BTW - if you have a problem then increase the DRAM Voltage 1.65v~1.68~1.70v. Lower voltage is better, but failure does you no good either and 1.65v DDR3 is fine up to +0.2v above spec, but if DRAM Voltage 1.65v~1.68 fails then increase DDR VTT Voltage Control -> +0.1v above Auto.
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April 18, 2011 10:50:17 PM

Ok so I just need to clarify. So I understand to take it off auto setting so that the bios doesn't change something on me when I uP it to 1600. I'm wonderingg about the voltage tho, as the spec for the 1600mhz ram I have on corsairs site says it's tested at 1.5 v. Shouldn't it be able to run at 1.5v then at 1600 with 9-9-9-24 2T settings? I'm just confused as to where the 1.65v comes in. Also I should mention I am currently getting help from a guy on this site saint19 in the overclocking section. I left the multiplier at 6.66 and bumped uP the fsb to 250, while lowering the ht and NB multiplier. So currently I'm running prime 95 at 3.5 ghz CPU clock, 2 ghz NB and ht, and 1666 MHz for the ram. So far it's been on for almost half hour with little temp change. Should I have bumped up that voltage or...


Thanks again!
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a c 347 } Memory
April 18, 2011 11:12:26 PM

As I clearly said 'per spec' as of yet you never linked your RAM on this post --- so I've been guessing all along. Yes, manually set as I provided 'per your RAM's spec.'

RE Prime95 most bad stuff happens in 5~10 minutes and the temps stabilize. When everything is said and done you'll want to run Prime95 overnight for a full CPU burn-in.

Set Memory Clock -> 6.4 ***{if available} ; 6.67 X 250 = 1668 no big deal; 8 X 200 = 1600 MHz ;
DRAM Configuration / Enter
Set the CAS timings ; per spec e.g. 9-9-9-24
Set 1T/2T Command Timing - 2T
--
DRAM Voltage Control -> 1.50v ; failure 1.58v~1.60v

CPU:
2800 / 200 = 14 ; stock
3500 / 250 = 14 ; 3.5GHz 25% OC
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April 18, 2011 11:48:11 PM

My apologies jaquith I figured that's what you meant but for whatever reason I had thought that I had mentioned that info when indeed I hadn't so right on. Prime95 has been on for an hour. I guess if you say he bad stuff usually happens 5-10 min in then I should be ok at the current. You mentioned that in the event of a failure to bump up the memory voltage. Would I also be increasing the necessary CPU voltages at that point too as I assume you couldn't determine if it was strictly the memory that had the issue?

Once again I really appreciate all your help on this I know the topic has strayed a little but THANKS once again!!!!!
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a c 347 } Memory
April 19, 2011 2:37:26 PM

Some Vengeance kits were 1.65 and most newer kits are 1.5v, but if you set 1.50 at 1.65 it wouldn't do a thing wrong; RAM has a tolerance of ±0.2v. Less is best; Voltage = Heat.

The problem is you're trying to do 2 things at once, but I would seriously doubt that any instability would be coming from the RAM unless the RAM is 'bad' itself.

Therefore, 9.9/10 if you're having any instability, hopefully you're not, it's coming from the CPU OC. Dialing in a CPU OC is a little more complex than a FSB or CPU multiplier and up'ing the CPU voltage although an OC of 3.50GHz is easy.

After funning Prime95 you also need to run Memtest86+ and I recommend at minimum 2 passes if not 4 passes; note 12GB is also an overnight affair. The more the RAM to longer it takes, my assumption is a few hours.

Memtest86+, download the ISO/zip file and use it to burn a bootable DC/DVD -> http://www.memtest.org/

Good Luck! :) 
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April 19, 2011 10:16:05 PM

Ok good to know on the Ram voltage. Right now its working fine (but really its only working at its spec speed anyway). Tonight I am going to try to bump up my values a bit more. I will keep in mind what you said regarding the CPU most likely being suspect if I do run into stability issues.

Thanks Jaquith!
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