Why cant I get a stable overclock?

[1000FPS]

Okay so first of all here is my build:

Phenom II x4 955 (C2 revision)
GTX 460 768 OC'ed
Asus M4A78L-M motherboard
4GB DDR2 800 Ram
Windows 7 64 bit

Not long ago I bought a Scythe Katana 3 CPU cooler so that I could try and overclock my 955. The temperatures are very good (when CPU is at stock), idles at 28c and load is 45c. I turned off Cool 'n Quiet, and put the CPU voltage on manual settings (which I believe is 1.35v for my CPU) and tried overclocking using the multiplier (because its a black edition), but I cant even reach 3.4GHz without getting a BSOD. I tried upping the voltage by quite a lot, but it was still unstable and kept getting BSODs after a few minutes of Prime95. Also, I bought the 955 on ebay, and the previous owner said he had overclocked it to 3.7GHz stable. Is it just because my motherboard is crappy at overclocking? Btw its completely stable at stock speeds, but the reason I want to overclock it is because Ive noticed it is bottlenecking my GTX 460 in some games (CPU usage is at 100%). And how much voltage do you think I would need to reach 3.6?

Cheers

 

[xaira]

leave the voltage on auto, enable advanced clock calibration

 

[smithereen]

The C2 revision of that processor is rated up to 1.5V. If I was overclocking, I would set the voltage to ~1.45 for starters, if your temperatures are under control. That board is not the best. Set ACC to auto, that should help a little, and increase the multiplier slowly. You should get results that way. Are you using AOD, or the BIOS for your overclocking? Using AOD makes it easier to roughly find your headroom, if you have patience. Once you've found settings you like (and you're sure are stable, set them in the BIOS.

 

[1000FPS]

The C2 revision of that processor is rated up to 1.5V. If I was overclocking, I would set the voltage to ~1.45 for starters, if your temperatures are under control. That board is not the best. Set ACC to auto, that should help a little, and increase the multiplier slowly. You should get results that way. Are you using AOD, or the BIOS for your overclocking? Using AOD makes it easier to roughly find your headroom, if you have patience. Once you've found settings you like (and you're sure are stable, set them in the BIOS.

Thanks, I will give it a try. What does ACC actually do?

 

[xaira]

i dont know, but before acc, u get a 200mhz oc, and after acc the sky is the limit, at least from personal experience

 

[1000FPS]

The C2 revision of that processor is rated up to 1.5V. If I was overclocking, I would set the voltage to ~1.45 for starters, if your temperatures are under control. That board is not the best. Set ACC to auto, that should help a little, and increase the multiplier slowly. You should get results that way. Are you using AOD, or the BIOS for your overclocking? Using AOD makes it easier to roughly find your headroom, if you have patience. Once you've found settings you like (and you're sure are stable, set them in the BIOS.

Okay I set the voltage at 1.4, and its clocked at 3.6. Been running Prime95 for 40 minutes stable. I didnt realize that it needed so much voltage. How long should I run Prime95 before I can safely say that it is 100% stable? 4 hours?

 

[smithereen]

Overnight should be fine. You should be able to get a higher AC with a little more voltage, though.

 

[1000FPS]

After about an hour I got another BSOD, so then I put the voltage up to 1.46, Ive got Prime95 running ATM, no crashes yet. I also tried running it at 3.7, with the voltage at 1.49, but it crashed after 5 minutes. It looks like Im needing to give it lots of voltage just to give it a relatively small overclock. Could it be possible that Im giving it TOO MUCH voltage?

 

[Wisecracker]

After about an hour I got another BSOD, so then I put the voltage up to 1.46, Ive got Prime95 running ATM, no crashes yet. I also tried running it at 3.7, with the voltage at 1.49, but it crashed after 5 minutes. It looks like Im needing to give it lots of voltage just to give it a relatively small overclock. Could it be possible that Im giving it TOO MUCH voltage?

very much so

And you should try OC'ing with the clock. Drop the volts and the memory ratio one notch, and try 15X230MHz. You're all over the place, and we need to isolate what you can do to reach your best clocks.

You should also list what type of RAMs you have, and your power supply.

 

[smithereen]

What wisecracker said. It's a game of patience. Fiddle a little here, fiddle a little there. It tends to be best for longevity to keep the voltage as low as possible, but I wouldn't worry two much, especially since your CPU is rated so high. For the record, I got 3.8 at 1.45V with an unlocked dualie, and the sweat spot has been 1.425-1.475V has been the ideal range for all the C2 Phenom II rigs I've built or OC'd.

 

[1000FPS]

What wisecracker said. It's a game of patience. Fiddle a little here, fiddle a little there. It tends to be best for longevity to keep the voltage as low as possible, but I wouldn't worry two much, especially since your CPU is rated so high. For the record, I got 3.8 at 1.45V with an unlocked dualie, and the sweat spot has been 1.425-1.475V has been the ideal range for all the C2 Phenom II rigs I've built or OC'd.

Ive come to the conclusion that I have a crappy mobo for overclocking, because I just cant get it stable above 3.6. Ive tried a whole range of voltages, tried ACC but nothing works. But I have heard somewhere that OC'ing your North bridge can sometimes make OC'ing the CPU easier? It that true?

 

[iam2thecrowe]

Also, the voltage you set in BIOS may not be the actual voltage. I have mine set to 1.35v in BIOS but hwmonitor reports as 1.28v?? Maybe check your actual voltage.

 

[Wisecracker]

There are limits as to OC'ing with the unlocked cpu multi. Some chips take a much higher multi than others -- that is why you should at a minimum learn the basics of OC'ing with the clock, and isolating operations and settings that effect performance.

It also helps you learn the inter-relationships between system components, and the *jargon* or terms associated with OC'ing so that we may communicate clearly with one another.

Reading and understanding a standard AMD Overclocking guide may be of benefit to you.

 

[1000FPS]

There are limits as to OC'ing with the unlocked cpu multi. Some chips take a much higher multi than others -- that is why you should at a minimum learn the basics of OC'ing with the clock, and isolating operations and settings that effect performance.

It also helps you learn the inter-relationships between system components, and the *jargon* or terms associated with OC'ing so that we may communicate clearly with one another.

Reading and understanding a standard AMD Overclocking guide may be of benefit to you.

Ive never overclocked with the clock before, not too confident but Im going to read some overclocking guides. Thanks for all the replies