Overclocking Athlon II X4 640

I OC'd my Athlon 2 X4 640 to 3.45 GHz at stock voltage. How do I know whether I need to increase the voltage or not? My bios only allows me to increase the voltage in increments of .05, so I was hesitant to increase it. My voltage right now is 1.392.

The system is stable (I ran a prime95 stress test) and the cpu hits around 64C under max load. While playing games, it never goes above 51C.
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  1. Best answer
    if the system is stable when testing under prime95 then you do not need to increase the voltage you are good to go. 1.392 does not seem like a stock voltage that seems very high are you sure you did not leave the voltage setting to auto? if you did then the motherboard has increased the voltage for you so it is not stock
  2. No, the voltage is not auto...On the amd website it says the stock voltage for the cpu is 1.1 - 1.4. Also, I'm planning to get a GeForce gtx 560. Will my cpu bottleneck the card?
  3. Best answer selected by pmarathe25.
  4. what resolution are you going to play at? I think you will be fine with that cpu if you keep it at the OC'ed settings...maybe try to drop the vcore a little bit it probably doesnt need to be that high for those speeds.
  5. The motherboard won't let be drop the voltage. There are only 5 settings - default, +.05V, +.1V, +.15V, and +.2V.

    I'm playing at 1920x1080.
  6. yea you will be fine with the 560....try setting it to the +.1v setting and if your vcore is like 1.2v-1.3v see if thats stable...test each setting then tell me what the voltage is for each setting use cpuz to determine it
  7. Okay..tried +.1V. CPU-z shows that the voltage is 1.504. I ran prime95 and the temps went to 74C after 10 minutes, so I shut it off (the max temp for my cpu is 71C according to the amd website). with default, the voltage dynamically adjusts according to cpu load anywhere between 1.092 and 1.392.
  8. seems like auto is the best bet for you then.....not a good oc board unfortunately
  9. yes, it's a Biostar A880G+ microatx board.
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