Overheating VRM at stock temps causes auto restart?

Aug 5, 2018
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I've recently bought a used P7H55-M from aliexpress and paired it with my Xeon x3450. After some time my computer auto restarts ( no overclocks mind & temps on GPU/CPU were super good) without BSOD (Automatically restart turned off) and I'm able to use it normally but after a few minutes, it'll auto restart again, with the interval between each auto restart decreasing.

After switching back to my old MOBO for a couple of days, I've decided to use the P7H55-M again. This time, I've re-applied the thermal paste on the chipset heatsink and removed the thermal pad on the MOSFET heatsink. It ran without problem and was able to OC but after a few days, the auto restarts came back.

Question is do I really need thermal pads between the MOSFET and heatsink and why did it run fine with OC for a few days without thermal pads?
 
Aug 5, 2018
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I'm running a Hyper 212 Turbo LED. It's highly unlikely that the CPU is the issue because

1) temps are very safe.

2) system works flawless with a different MOBO
 

kanewolf

Titan
Moderator


If you were running and AIO water cooler, that would provide no airflow over the VRMs. That is why I asked the question.
 

mortemas

Reputable
Feb 11, 2015
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Wait, what? You absolutely need the thermal pads on the mosfets. They are high current devices and need to dissipate the heat through a heatsink. You were getting lucky in the beginning and that’s why they still worked without the thermal pads. The auto restart is one problem, but removing the pads will create another. Reminds me of a Top Gear episode where they drove a car without motor oil in it. It ran for longer than you would think, but it definitely killed the engine eventually.
 

kanewolf

Titan
Moderator


One problem is that motherboard doesn't officially support the CPU you are using. It could be a simple as the BIOS doesn't know how to properly deal with the CPU.
 
Aug 5, 2018
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Thanks. WIll try to put on thermal pads and post an update. Does the quality matter much? Reason I removed it because the MOSFET heatsink was just a little warm, not hot, when the CPU was under full load. My guess is the old thermal pad was not passing heat because it could be really old/ low quality.
 

mortemas

Reputable
Feb 11, 2015
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Yeah, the pads come in different levels of thermal conductivity. The best I think are Fujipoly. They have “extreme” and “ultra” pads, but even the extreme are going to be better than most other brands in conductivity. Do you still have the old pad(s)? You need to know what thickness to buy. It comes in 0.5, 1.0, 1.5 mm thickness, maybe thicker too.
 
Aug 5, 2018
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There are lots of youtube videos with this cpu & mobo pair. And I'm already using the BIOS version. If the BIOS for whatever reason doesn't support my CPU then shouldn't my computer not boot at all?
 

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