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Is my understanding of Core2Duo overclocking right?

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May 31, 2007 2:58:02 PM

Hi all, this is my second ever post in THWG forums so please excuse my lack of know how...

Ok, to start things off, my rig is as follows.

DFI Infinity 975x/g mainboard
Jeantech Storm 700w PSU
Core2Duo E6600 (at stock levels currently)
OCZ Reaper PC-9200 (rated to achieve 1150Mhz)
1 x 300gb Samsung Spinpoint (SATA Boot)
3 x 250gb Samsung Spinpoint (SATA Storage)
2 x DVD-RW (Single and Dual Layer)
Soundblaster X-Fi Extreme Music and lastly
2 x X1950XTX Crossfire.
1 x generic aluminium case.

Okies, so the basics are there.

After reading some of these pages here (learning as I go) I've come to the following conclusions:

E6600 advertised at 1066fsb is really 266fsb in bios (quadpumped)
CPU:D RAM ratio of 1:1 gives me 266fsb/DDR2-533mhz (266Mhz x 2 for Dual Channel)
2.4Ghz is 266Mhz with a 9 x multiplier...

So, the burning question... In theory of course, should I be able to achieve RAM speeds at the stated 1150Mhz, giving me an FSB on 1:1 CPU/DRAM ratio of 575Mhz with a multiplier of 6 to get me 3450Mhz?

From what I've read and understood, the math makes sense there, but figuring out what could potentially become a holocaust in my PC is a bugger.

I've read the C2D Overclocking Guide V1.1, but on my mainboard, the bios options are many and I don't really have a clue what each of these options does.

If someone could give me a few pointers, that would be fantastic.

Many regards

Insomnai
May 31, 2007 4:52:02 PM

You will probebly don't hit a 1:1 overclock with the ram on 1150 MHz cause of the motherboard. You can give it a try, but I don't think you will get that high FSB's with an 975X... Even with an 965 motherboard its pretty difficult to get there.... And mostly 965's are higher clockers....

But, why should you down your multiplier that much..... Just use something like an 2:3 relation, en than see how high your cpu wants to go on an 9X multiplier... That will already give you 3.46 GHz... Pretty high if you ask me...

Succes with it..
May 31, 2007 5:30:56 PM

Quote:
I've read the C2D Overclocking Guide V1.1, but on my mainboard, the bios options are many and I don't really have a clue what each of these options does.


This is your problem:

Quote:
DFI Infinity 975x/g mainboard


DFI boards are for overclocking pros. They have 6x the BIOS options that normal mobos have. You can learn the options but it is going to take alot of time and alot of the options you shouldn't ever touch. DFI uses more precise naming on most settings than most mobo manufacturers also.

As for the 575FSB you will never achieve that on a 975 chipset, nor a 965 chipset. The only chipset that can achieve this with air cooling (or water) is the new P35. With the 975 you be lucky to break 430-450. :?
Related resources
May 31, 2007 5:50:03 PM

How old is your e6600 (Older the Better)? Cause it is my experience that the post-price drop e6600 overclock terribly bad. 1.475v isnt enough for mine to run stable @3200mhz. I have the newer 260$ e6600.
June 1, 2007 4:06:24 PM

so.... more questions :-)

Quote:

As for the 575FSB you will never achieve that on a 975 chipset, nor a 965 chipset. The only chipset that can achieve this with air cooling (or water) is the new P35. With the 975 you be lucky to break 430-450.


Is there a particular reason that the FSB cannot go that high? From my understanding, the FSB and multiplier combined give me a speed in Mhz on the CPU, so what if I lowered the multiplier? Does the higher FSB still cause problems for something else?

Quote:

How old is your e6600 (Older the Better)? Cause it is my experience that the post-price drop e6600 overclock terribly bad. 1.475v isnt enough for mine to run stable @3200mhz. I have the newer 260$ e6600.


It is literally just a couple weeks old. Bought it from Overclockers UK for £140. Trying to find a couple of good utilities to tell me the stepping codes etc.

If what you say is true, then I might have fallen short with the slower rated cores.

Ok, more questions, regarding voltage, for the sake of understanding... How do you know when to move the voltage up or down? Is there something specific I need to look out for?

Something I noticed about my system last night too, according to CPU-Z, my memory is running at a CPU/Dram devider of 2:3 giving me 800Mhz memory vs 266FSB, however, it feels slower and more sluggish... brief pauses in activity before applications start up or respond... is this normal?

Regards and thanks again


Insomnai
June 1, 2007 5:09:02 PM

Quote:

Is there a particular reason that the FSB cannot go that high? From my understanding, the FSB and multiplier combined give me a speed in Mhz on the CPU, so what if I lowered the multiplier? Does the higher FSB still cause problems for something else?


it depends on the chipset and on the motheboard, most mobos just can't handle that kind of fsb

Quote:
It is literally just a couple weeks old. Bought it from Overclockers UK for £140. Trying to find a couple of good utilities to tell me the stepping codes etc.


u dont need no utility, if u still have the box it says in there on the side, what week wat model n batch u have, and if u dont have the box, u can always look at ur cpu, its written in te IHS but for this u would have to unassemble ur computer

Quote:
Ok, more questions, regarding voltage, for the sake of understanding... How do you know when to move the voltage up or down? Is there something specific I need to look out for?


well wat u do...is... find out what speed u wanna achieve say 3.0 on a e4300 it would be 333x9 say do a 1.4v on the cpu, then u test it with orthos or with sp95, if it runs fine, then u can lower the vcore by 0.125 then u run orthos again... if its stable u keep lowering the vcore, or u can do the other way, where u start really low, (somtimes ur computer might not even post, then work ur way up, testin with orthos n sp95

Quote:
Something I noticed about my system last night too, according to CPU-Z, my memory is running at a CPU/Dram devider of 2:3 giving me 800Mhz memory vs 266FSB, however, it feels slower and more sluggish... brief pauses in activity before applications start up or respond... is this normal?


try to keep the 1:1 fsb:ram so ur memory should be runnin @ 667 u wont feel any real time performance loss.
June 1, 2007 5:44:56 PM

I got the code off my box:

L640A824

According to various sources, the E6600 I have should be able to do 3.5Ghz @ 1.48v, 3.6Ghz @ 1.55v and 3.7Ghz @ 1.58v...

Ok, so I need to find a way to keep my memory with 1:1 ratio to the CPU... I shall read the good book of DFI. I think it is done through the "System Memory Frequency". I'll take a look. just out of curiosity though, why would I have memory at 667mhz if my FSB is 266Mhz? Don't you mean 533Mhz or did I miss something?

Chap 1 vs 23. "There shall be an overclock and it shall be good".

Regards

Insomnai
June 1, 2007 6:04:10 PM

Quote:
so.... more questions :-)


As for the 575FSB you will never achieve that on a 975 chipset, nor a 965 chipset. The only chipset that can achieve this with air cooling (or water) is the new P35. With the 975 you be lucky to break 430-450.


Is there a particular reason that the FSB cannot go that high? From my understanding, the FSB and multiplier combined give me a speed in Mhz on the CPU, so what if I lowered the multiplier? Does the higher FSB still cause problems for something else?

Yes, it is just a chipset limitation. I don't know if the problem is physical, design issues, manufacturing problems or what. Lowering the multi won't help the overall FBS limit on the board. 975 chipsets max out somewhere in the mid 400's, 965 typically max out around 500 as do 680i board, the P35 is able to do achieve 550+ FSB so far.

Gigabyte P35


Quote:
Ok, more questions, regarding voltage, for the sake of understanding... How do you know when to move the voltage up or down? Is there something specific I need to look out for?


If you OC in small intervals (3-5MHz at a time on the FSB), then you should see your computer restart when put under load if it is undervolted slightly. If it is severely undervolted then the computer should lock up. No harm will be done to your computer in either of these situations, but in order to stabilize it you will obviously need to up the vcore.

Quote:
Something I noticed about my system last night too, according to CPU-Z, my memory is running at a CPU/Dram devider of 2:3 giving me 800Mhz memory vs 266FSB, however, it feels slower and more sluggish... brief pauses in activity before applications start up or respond... is this normal?


That maybe just seek times on your hard drive. Defragmenting it regularly helps. I doubt it is a problem with your RAM, although if a latency setting is severely misconfigured it is possible, but unlikely.
June 1, 2007 6:43:59 PM

yeah 533 i meant :D , :]
June 24, 2007 10:52:32 PM

just thought I would update my post with the latest results...

E6600 @ 2.4ghz running stable at 3.0ghz!

Done by removing the reference heatsink and placing the old faithful Scythe Mine Cooler (from my old AMD setup) with the included LGA775 brackets.Temps at 2.4ghz dropped from 54c doen to 34c idle.

Temps under load (encoding multiple files to DivX) never go past 57c. Northbridge on my 975x/g board settles at 67c as it has that ceramic passive cooler plate on it, which doesn't seem to bother the system at all. Might put a better cooler on that one.

3dMark05 scores went from 15300 to 17400 (at 2.9ghz, not tries new bench yet!).

Overall I'm pretty pleased with the results so far!

Regards, Insomnai
a b à CPUs
June 24, 2007 11:51:36 PM

Quote:
just thought I would update my post with the latest results...

E6600 @ 2.4ghz running stable at 3.0ghz!

Done by removing the reference heatsink and placing the old faithful Scythe Mine Cooler (from my old AMD setup) with the included LGA775 brackets.Temps at 2.4ghz dropped from 54c doen to 34c idle.

Temps under load (encoding multiple files to DivX) never go past 57c. Northbridge on my 975x/g board settles at 67c as it has that ceramic passive cooler plate on it, which doesn't seem to bother the system at all. Might put a better cooler on that one.

3dMark05 scores went from 15300 to 17400 (at 2.9ghz, not tries new bench yet!).

Overall I'm pretty pleased with the results so far!

Regards, Insomnai


I have the same board and for its money it's exemplary!!! You will easily do more than 450MHz on the board if you have the 2nd revision and flash the latest BIOS. I would point you to the DFI Street site, but you are unlucky as it closed down a couple of months ago. It had all the secrets and tweaks for our mobo. Now the bridge with the ceramic heatsink on top is your Southbridge and not the Northbridge. For high o/c i suggest you replace the Northbridge cooler. I use a thermalright HR-05 SLI, link here: http://www.sidewindercomputers.com/thhrsli.html

It dropped my temps from 67-68oC load to 55-57oC, and idle from 60oC to 46-48oC. It simply rulez! hehe
June 25, 2007 11:35:57 AM

I ran the 3dMark05 bench again while the CP was set to 3.0ghz and was a little amazed at losing over 4000 marks...??!?!?!

the CPU running at 2.9ghz produced a nice result of 17835marks while the 3.0ghz setting gave me a shocking 13300...

Anyone have a clue what happened here or have I discovered a nice little sweet spot with this chippie?

Regards

Insomnai
June 25, 2007 3:39:12 PM

Quote:

I would point you to the DFI Street site, but you are unlucky as it closed down a couple of months ago.


Aaah, well, the www.diy-street.com site is running fine and well, looks like a rename. heheheh

Regards

Insomnai
a b à CPUs
June 26, 2007 12:16:14 AM

Quote:
I ran the 3dMark05 bench again while the CP was set to 3.0ghz and was a little amazed at losing over 4000 marks...??!?!?!

the CPU running at 2.9ghz produced a nice result of 17835marks while the 3.0ghz setting gave me a shocking 13300...

Anyone have a clue what happened here or have I discovered a nice little sweet spot with this chippie?

Regards

Insomnai


You probably changed the FSB and you dropped to another strap, forcing the Northbridge to increase its timings to compensate for the extra MHz.
a b à CPUs
June 26, 2007 12:18:01 AM

Quote:

I would point you to the DFI Street site, but you are unlucky as it closed down a couple of months ago.


Aaah, well, the www.diy-street.com site is running fine and well, looks like a rename. heheheh

Regards

Insomnai

Yes that is the new site, but it is not the same as the old one, as it no longer officially supports DFI. It used to, but DFI and the site managers didn't agree on some things and they decided to follow their own way.
You might still find some usefull stuff in the forums, but some stuff was deleted during the transformation.
June 26, 2007 6:43:23 AM

Quote:

You probably changed the FSB and you dropped to another strap, forcing the Northbridge to increase its timings to compensate for the extra MHz.


What would my my northbridge decide to do that? Also, I had no idea that the northbridge had timings of its own to alter! sigh... soo much to learn hehehe.

Is there somewhere detailed that I can read up on this? I'd like to know more...

Quote:

Yes that is the new site, but it is not the same as the old one, as it no longer officially supports DFI. It used to, but DFI and the site managers didn't agree on some things and they decided to follow their own way.
You might still find some usefull stuff in the forums, but some stuff was deleted during the transformation.


Yeah after doing some reading there the site felt different and lost the kick it once had. Shame. I remember it being a good site!

Many regards

Insomnai
a b à CPUs
June 27, 2007 6:17:28 AM

Quote:

You probably changed the FSB and you dropped to another strap, forcing the Northbridge to increase its timings to compensate for the extra MHz.


What would my my northbridge decide to do that? Also, I had no idea that the northbridge had timings of its own to alter! sigh... soo much to learn hehehe.

Is there somewhere detailed that I can read up on this? I'd like to know more...

Quote:

Yes that is the new site, but it is not the same as the old one, as it no longer officially supports DFI. It used to, but DFI and the site managers didn't agree on some things and they decided to follow their own way.
You might still find some usefull stuff in the forums, but some stuff was deleted during the transformation.


Yeah after doing some reading there the site felt different and lost the kick it once had. Shame. I remember it being a good site!

Many regards

Insomnai

Here is exactly what you need: http://www.thetechrepository.com/showthread.php?p=32

It explains pretty much how the northbridge works, and it even mentions the 975x which we have in the DFI mobo. That should help you understand how the system works more or less. For more info you can google: northbridge, fsb, strap, timings etc...

I got some nice mods for the DFI, managed to snap them from diy street before it closed down. Don't have them here though, i am in the office and i got them home. Don't have internet at home yet, as soon as i get it online i could post them to you if you are interested. So do your homework first and by the time you are ready i should be ready to post you the mods.
June 28, 2007 4:28:13 PM

That would be great, looking forward to trying those mods out thank you...

I had no idea that the northbridge effected things to much.

Was great reading.

Regards

Insomnai
!