Cpu + gpu overclock, power problem?

Hi everyone, 

I'm not experienced a lot in overclocking so I have behavior that I don't understand and thats stopping me from overclocking more.

Start from the beginning i had a 700w ocz power supply. When I overclocked my e8400 cpu to 3.6 and my gtx 260 core clock to 680 I was stable when running gpu bencmark but while gaming my coreclock was randomly  getting down and my fps was down until I restarted. 

After some search I understood that my gpu drived was crasing when my cpu was under heavy load. So I used prime95 blend test and kombuster at the same time and my driver crashed always until I got my gpu core clock to 640 mhz. That was desapointing, but I was sure that it was a power issues.

So i changed my psu ( that I tough was really enough before these incident) to a high current pro 850W.

Received it, mounted it and with prime 95 blend test at the same time as kombustor I can get my gpu coreclock to 700 mhz.

But if I do a intel burn test paired with kombustor the driver crash.

Am I testing too much? Is that something i'm missing?

E8400 3.6 ghz with 1.2v under bios.

I would like to push it to 4ghz but for stability in 100% cpu + 100% gpu i would have to push my gpu not near as far as now.

Sorry for the long post and the bad english ( not my first langage )
5 answers Last reply
More about overclock power problem
  1. You are testing under more strenuous conditions than I ever have.

    Try each test individually. Then play some demanding video games. (check your max temps from each session.)

    If all is well. Enjoy your rig.
  2. Ok, thank you Z1NONLY,

    I made these test because it helped me find the problem I was getting while playing some cpu demanding game.

    When I play Borderland 2 my cpu is always near 100%.

    Well, I will make sure that each one is individually stable and play games to see.

    If I got the same problem again I'll come back and tell it.
  3. Since Kumbustor + prime 95 work but not Kumbustor + Intel burn test, I suspect that your CPU OC may need some tweaking.
  4. When you say some tweaking you would start where?

    Bumping a little bit the vcore?

    And I still try to figure why my PSU switch helped me get higher core clock on my gpu?
  5. Bumping Vcore if you have the headroom and your temps don't suffer.

    Basically, to get stable, you need more voltage or less speed.

    The PSU is the foundation on which everything is built. Weak/unstable/out-of-spec power will limit your OC. The faster you go, the smaller the allowable margin of error.
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