CPU dead after reapplying thermal paste?

JasonTheMiller · November 7, 2018

Motherboard: MSI Z270 tomahawk

CPU: Intel i5 6700k

CPU Cooler: Cooler Master hyper 212 evo

GPU: Asus ROG Strix GTX 1060 6gb

Memory: 1x Corsair Vengance 16gb ddr4

I have the full details below, but the TLDR is I went to reapply thermal paste due to temperature issues I was noticing, noticed a nut fell out the back of cooler stand when reapplying thermal paste, applied too much thermal paste, ignored the nut(did remove it to not cause a short) booted pc and had it work fine, then it spam shut down and rebooted, took it completely apart and redid everything properly, noticed CPU would no longer boot, and MOBO ez debug light was indicating CPU issues, cant figure out why.

So I was having issues with overheating for a while in my CPU on a one year old build. My GPU and all other items were perfect and stable, but my CPU fluctuated very heavily jumping between 40-80 degrees constantly, I cleaned out my PC with air, noticed the same problems so figured since everything else was fine and my pc was dust free, it must be the thermal paste, the PC operated fine as I ordered the thermal paste and waited a week for it to arrive, I gamed constantly during that period and it ran perfectly fine and didn’t have issues. The day the thermal paste arrived I took my cooler off, wiped the CPU and heat sinks with isopropyl alcohol and cotton swabs, as I had done before, then I noticed the nut in the back of the cooler stand had come off, I cleared it away from the MOBO so it wouldn’t cause a short, not wanting to disassemble the whole thing for what should be a very quick and simple maintenance, I ignored that there was a nut missing, especially since I was still able to tighten the heat sink fairly well to the MOBO and CPU. Now I want to add I did put too much thermal paste as well, definitely not to the point where it leaked into the socket, but it did get onto the edges of the lid and later on when I removed the heat sink from this particular application, I noticed the paste had scattered away from the center. My application was a fat line instead of a pea sized dot, which was a mistake. I brought it back to my room and hooked it up, it ran fine for a good 10 minutes, then it suddenly shut down and rebooted, it shut down and rebooted 2 more times before it would even load up the windows screen. Once it did load up, I opened the thermals to monitor the CPU temps, still having the fluctuation issue even with freshly applied thermal paste, so I shifted my attention to the one other thing it could be, the nut that I ignored, but at this point it was late in the night, so I didn’t want to disassemble at this hour, so I tried just hand checking to make sure everything was a tight fit and the heat sink was sitting properly on the CPU, it was a little crooked, so I realigned it and made sure everything was tightly fastened, CPU booted for 5 minutes I kept thermals monitored, the fluctuation issue was not resolved then it shut down and rebooted again, within the next 20 seconds it proceeded to continue shutting down and rebooting 4 more times before I quickly pulled out the cords to stop the power from running through it. I went to bed and took it the next morning to my workstation again, disassembled made sure the nuts were on properly, really put a lot of attention to detail, cleaned and reapplied the proper amount of thermal paste, and brought it back to my room. Case lights turned on, GPU lights turned on, MOBO lights turned on, all fans spinning, I was relieved then I realized I wasn’t getting signal on my monitor. I reinspect everything and realize the EZ Debug light from the MOBO is on, and it’s on the CPU section, meaning it’s not detecting a CPU or the CPU is failing to post. I shut it down again removed the cooler and CPU, took the CPU out of the socket for the first time and inspected it thoroughly with a magnifying glass, did not see anything in the socket, no thermal paste, bent sockets, hairs or any other object that could obstruct, checked the CPU and it appeared to be in perfect condition, reseated it properly, lining up the triangle, and still it would not post and the light remained on, I pulled it out, inspected, and reseated it 2 more times to no avail. It will not boot up, and I will not get signal to any monitor through any display, even after removing the GPU and focusing on receiving video display directly from the MOBO it failed, leaving me with no display to look at, and potentially a dead CPU. I did the battery reset and all that, I double and triple checked that all the CPU cables were connected where they needed to be, but nothing has worked, has my CPU fried, did I cause problems in my MOBO? It’s hard to tell since it won’t post and there’s no obvious signs on either the CPU or the MOBO that one is damaged, besides the CPU debug light being on, on my motherboard. I do not have any other rigs to test my equipment on. Does anyone have any idea what may have happened to my system? My suspicion is when I ignored the nut in the back I was unable to get a 100% properly situated heat sink sitting on the CPU and perhaps a microscopic lack of a contact point, caused the thermals to go crazy in the CPU overheating and frying it until it became unusable. I may be wrong though, this was my first build and I barely made it last year, and haven’t paid much attention to PC related stuff since then, so I’m not PC knowledgeable enough to know if that’s right, would really appreciate any insight.

Jonathon1107 · November 7, 2018

Seems like a long list of things you did and ignoring anything even as small as a loose nut in something as valuable and sensitive as a PC can cause issues, it’s always best to do everything thoroughly the first time around. Best of luck.

mxk · November 8, 2018

wow the huge font and the essay made this a nice read. I agree with this dude above me ^^^^^ and it sounds like theres a lot of things that you neglected that shouldn't be when building and one of the many things you missed could be the issue. Next time around play nice i guess.

Brent744 · November 8, 2018

Remove all cords from the tower, every single cable (monitor, usb, mouse, etc.). Hold power button for 30 seconds to discharge any power that could be left, Then clear CMOS. The power from a video cable is even enough to keep the CMOS from completely clearing. Remove CPU, clean it again and with a magnifying glass I would inspect the socket for any damage and inspect under the CPU to ensure no damage or dirt/debris is present. Replace CPU with half pea size dot in center and replace cooler. Enter bios and "Load optimized defaults". Reboot and see if it boots to Windows. Your initial post says you have an i5 6700k, I assume you mean an i5 6600k or an i7 6700k.

Was the CPU overclocked? or running at stock speeds?