CPU heating up at idle

By vomacka
Mar 9, 2012
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  1. I recently replaced my old 400w PSU with a new 500w one.

    On the old 400w the cpu ran at 47c (Running FF) and the cpu fan at 4327rpm. It would stay at this temp all the time.

    On the new 500w the cpu now runs at 51c (Running FF) but the cpu fan now runs FULL SPEED 5444rpm after 10 minutes of computer use.

    Is it possible that the 500w psu is putting out more current to the cpu, thus making it run hotter and making the cpu fan run faster?

    Also, the old 400w psu has a 20 pin power connector, and my cpu temps were low all day. The new 500w psu has a 20+4 pin connector and now my cpu temps are higher than normal and my fan is running at MAX rpm to maintain 50c after ten minutes and never go down??

    I heard that perhaps the extra current from the extra 4 pins on the motherboard power connector could make the CPU run hotter?

    I had no problems when I was using a 20 pin connector. The temps were low and stayed low all day long.

    Any ideas?



    My cpu fan, as I type this, is running at 5444rpm. NOISY.

    I also plan on installing a 80MM case fan as a precaution.

    Motherboard: ASUS M3A AMD AM2 Quad core CPU support
    CPU: AMD Athlon 64 X2 6000 Dual Core
    PSU: Enermax 500w
    Memory: Kingston 1Gb 240-Pin DDr2 SDRAM DDR2 800 (x2)
    Video card: ATI Radeon X1550 256Mb
  2. mailpup

    mailpup TS Special Forces Posts: 6,876   +332

    Ernamax 500w? Do you mean Enermax? If not, what are the PSU's specs? Did you take anything apart besides the PSU connections? Could you have knocked the CPU heatsink loose accidentally? In any case, try removing the heatsink, clean off the old thermal compound and reapply fresh thermal compound.
  3. Sharkfood

    Sharkfood TS Guru Posts: 1,019

    The CPU has a voltage regulator to ensure proper feed so the new psu rating will not impact feed unless it was somehow functioning with undervoltage before (highly unlikely).

    What is more likely is that the old PSU probably had better airflow or even a bottom mounted fan that your new PSU does not have, thus creating more airflow near the CPU heatsink. It's also possible that maybe some dust-bunnies have found their way in the CPU heatsinks when you did the swap.

    Overall 51c is really not that bad for idle temps. Do you have any other issues from the higher temps?
  4. vomacka

    vomacka TS Enthusiast Topic Starter Posts: 64

    Good point..

    Actually Sharkfood, you may be right.

    My old PSU had a variable fan speed switch (L,M,H,A). I had the switch on M all the time and I think that is what kept my idle temps at 47C. That temp gave me piece of mind that I was not pushing the CPU to hard. Also, the CPU fan did not run at a high spreed. (Oh BTW the CPU is only 3 months old)

    What is happening now is the new Enermax PSU fan does not rotate at the same speed as the old PSU, and it is not drawing as much air through the case. This is why I am going to add a case fan to see what happens.

    Right now, my CPU fan starts running at high speed 5 minutes after I turn the system on. That tells me that there is not enough air being pulled through the system box.

    Am I "in the ball park" on this one?



    Windows XP SP3
    Case: Dynapower Titan-C2702.25.M158 ATX
    Motherboard: ASUS M3A AMD AM2 Quad core CPU support
    CPU: AMD Athlon 64 X2 6000 Dual Core
    PSU: Enermax 500w
    Memory: Kingston 1Gb 240-Pin DDr2 SDRAM DDR2 800 (x2)
    Video card: ATI Radeon MSI R5670 1Gb
  5. vomacka

    vomacka TS Enthusiast Topic Starter Posts: 64

    Problem fixed..

    OK. I added a new exhaust fan and now the temps have dropped 5 degrees. Nice anf cool and the fan is only running at MAX 3000RPM.

    The problem was I did not have enough air passing into/through the case to cool the CPU.

    Thanks again.


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