Yeah, I know that I could ask this on any PC tech forum... But I just feel more comfortable asking it here. Because reasons.
So, I'm a (not so) proud owner of a Phenom x4 9500 mounted on an ASUS M2N-X Plus motherboard with a stock cooler. All that powered by a Chieftec 500W power supply.
I was using this stuff with a really ancient BIOS version and a HD5770. The BIOS supported my CPU, but didn't recognise its temperature properly - looking at HWINFO32 sensor data resulted in constant reading of about 54C. Well, everything worked fine (but the performance wasn't so great...).
But once upon a time, I got a R7 265 GPU (not my call). Once it arrived, I decided to update my BIOS to the latest version (was supposed to have a fixed temperature calculation algorithm for some CPUs) and replace my GPU. Well, i did manage to update the bastard, but I will never do it without an external flash programmer. Never ever again. (Irrelevant). Also replaced my GPU, cleaned and installed the drivers etc. Also started using a Phenom TLB workaround tool that I've found somewhere on the net (that performance boost is sweet). Everything works fine...
...except CPU clocks under load. Once the temperature reaches 57C, the clock is cut to half (1105 MHz) for several seconds, then it goes back to 2210MHz, everything is fine for half a minute (or less), then the drop repeats. On a graph, it looks like a PWM modulation of CPU clock speed in order to never exceed the temperature of 57C. The CPU has Tjmax of 70C, VRMs are barely warm, chipset temps look OK, I don't really think that this PSU will drop its voltages under that kind of load. The TLB workaround doesn't affect the problem (well, it does drop temps by about 2C in idle when the workaround is used).
So I've replaced the thermal compound under my cooler (to a cheap silicon one). Now the CPU throttles at about 55/56C.
Fiddling around with BIOS settings like Cool'n'Quiet and microcode updation (fixed someone's hecta-core t1060 with a similar problem), nothing.
Now, before I underclock my CPU a bit/slap a jet engine to my cooler/buy a new cooler with better thermal compound, I want to ask if any of you are familiar with such a problem, maybe someone might come up with something?
And well, if I had the cash to buy a good cooler, I would rather get some more cash and grab a 775 mobo with a modded 771 xeon and be over with it

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