Question Computer won't start up after thermal paste change.

Dec 15, 2019
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I was previously using old thermal paste scrapings from heat synks cut with toothpaste and it was working for awhile but then I started noticing this last month the cpu would sometimes get hot like into the 70's. so I bought fresh thermal paste cleaned the old thermal stuff off with a damp but not soaked wash cloth and added fresh thermal paste. I started the desktop and saw for under a minute the cpu temp went up to 92. but it dropped down the 60 something afterwords. I had a very gentle overclock enabled and from that point on the computer was constantly freezing so I removed the over clock no improvement. so I reenabled it, No dice, so I went to turn it off again and adjust some bios settings and then the thing developed a problem where it would automatically shut off before it could start, so I removed the cmos battery and left it without power for an hour and now it turns on but displays nothing and I'm using an asus z97 pro gamer and the red light that is for the cpu errors lights up when ever turned on and the cpu fan does not spin. I tried removing the cmos battery and leaving the computer off for 3 days but now it's doing the same thing still. Did I cook my processor somehow or is there something else wrong with it? the processor is 5 years old btw.
 
You should take off that cooler and re-apply thermal paste. Also, make sure your CPU cooler is tightened firmly.

When you remove thermal paste, for the love of God, don't use water. You either use isopropyl alcohol or atleast rubbing alcohol with a cloth(microfiber if you have). After cleaning the thermal compound make sure everything has dried out and re-apply.

Put a small blob(the size of a grain of rice) of thermal paste on the center of the CPU heat spreader. Make sure the CPU cooler is firmly tightened and makes proper contact with the CPU heat spreader before starting your system again.
 
Dec 15, 2019
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You should take off that cooler and re-apply thermal paste. Also, make sure your CPU cooler is tightened firmly.

When you remove thermal paste, for the love of God, don't use water. You either use isopropyl alcohol or atleast rubbing alcohol with a cloth(microfiber if you have). After cleaning the thermal compound make sure everything has dried out and re-apply.

Put a small blob(the size of a grain of rice) of thermal paste on the center of the CPU heat spreader. Make sure the CPU cooler is firmly tightened and makes proper contact with the CPU heat spreader before starting your system again.
So you don't think the processor got cooked by the 92 degree temp that it had for a bit under a minute?
 
So you don't think the processor got cooked by the 92 degree temp that it had for a bit under a minute?
You should list your full system specs too(CPU,mobo,RAM,GPU,PSU).

Answering your question: No, it shouldn't... if the temperature gets too high on the CPU the computer will shut off protecting itself from damage.
92C is really toasty indeed, but it should be below Tmax on haswell(I believe 100C is where it'll shut down on its own).

Follow the steps in my comment earlier.
 
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Darkbreeze

Retired Mod
Isopropyl alcohol IS rubbing alcohol. They are not two different things.

If it's a stock cooler of any kind, or an aftermarket cooler that uses spring clips or pushpins, then you need to use a lot more than a rice grain sized amount. More like about 1/3 of the exposed end of a number 2 pencil eraser, for low mounting pressure stock type coolers. Rice grain, and really, should be more like about three rice grains, should be reserved for coolers with high pressure mounting hardware that actually screws down to a bracket attached to the backplate.

Regardless, there is no way that a 92°C core temperature would cause any kind of permanent damage to any CPU, especially if it was only at that temperture for a brief time. So, no, that's unlikely.

What IS likely is that you have bent pins on the motherboard, and that is what you need to check for and where you need to start.
 
Isopropyl alcohol IS rubbing alcohol. They are not two different things.

If it's a stock cooler of any kind, or an aftermarket cooler that uses spring clips or pushpins, then you need to use a lot more than a rice grain sized amount. More like about 1/3 of the exposed end of a number 2 pencil eraser, for low mounting pressure stock type coolers. Rice grain, and really, should be more like about three rice grains, should be reserved for coolers with high pressure mounting hardware that actually screws down to a bracket attached to the backplate.

Regardless, there is no way that a 92°C core temperature would cause any kind of permanent damage to any CPU, especially if it was only at that temperture for a brief time. So, no, that's unlikely.

What IS likely is that you have bent pins on the motherboard, and that is what you need to check for and where you need to start.
Well, in my country they are 2 different things, the one with 70% is called differently from the 99% one. We call it rubbing alcohol the lower percentage one.
 

Darkbreeze

Retired Mod
Being in a different place does NOT change what a thing IS. It's the same, regardless of where you are in the world, but yes, I understand that some things are commonly known by inaccurate naming structures in some places. That's exactly why we have to correct it when it happens. 70% or 91%, it doesn't matter. They can both be called rubbing alcohol. There is no "99% isopropyl alcohol" except a very expensive lab quality offering through an extremely select few chemical suppliers.

100% of what you see on a store shelf or available through retail channels is mislabled, and is only 91% or the lower ratio 70%. In reality, the 70% is more effective for antimicrobial, antiviral and antibacterial usage, but as a solvent and cleaner/degreaser 91% is what you want, and it's what you want for cleaning off thermal paste.

Anything above 91% would either absorb water from the air so rapidly that it would become 91% or would simply evaporate faster than it could be used to serve any useful function except under specially defined lab conditions.
 
Dec 15, 2019
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Yeah I have a cooler where you screw the four pins into the motherboard. maybe they're not tight enough I could try that and if that don't work I could change the thermal paste again. would eye glasses cleaner work on the rag or cloth used to wipe the cpu? I do not believe it's any of the pins as I did not remove the cpu.
 

Darkbreeze

Retired Mod
Eye glasses cleaner would be better than water, but it may not be strong enough. If that's all you have though, then it's what I'd use. ONLY apply it to the cloth or paper coffee filter you are using to get it off with though.
 
Dec 15, 2019
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So you're sure the problem is the thermal paste job is bad? If I wash it off and put new stuff on again it will work? How could this cause the cpu to have a problem though preventing it from turning on?
 

Darkbreeze

Retired Mod
No, I don't think the thermal paste is your main problem. It is however A problem.

Thermal paste has nothing AT ALL to do with your CPU cooler not spinning up. Try connecting a different fan, case fan, whatever, to the CPU_FAN header on the motherboard to see if it spins like it's supposed to. If it does, and the current fan on your CPU cooler does not, then that is likely both the cause of your thermal problems AND your failure to POST. If your motherboard doesn't detect an RPM signal from the CPU cooler fan, it probably won't run, and will simply shut immediately back down. Or, if there is a short in the CPU cooler fan, it might detect that as well and simply shut itself off to protect itself from further damage.

Or, you may HAVE cooked the CPU if it had been running with a failing CPU fan for some time and you never realized it. If you try a different fan connected to the CPU_FAN header, and it pretty much NEEDS to be a four pin PWM fan just like the one on your CPU cooler, and it does NOT spin up, then it's highly likely you have a faulty motherboard.
 
Dec 15, 2019
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I was monitoring the temps carefully. It was never overheating for more than a minute at a time. I don't think I have a backup heatsynk fan. This one guy said changing the thermal paste again should fix it but I don't see how changing thermal paste in the first place would break it. but it seems to have.
 

Darkbreeze

Retired Mod
It wasn't overheating for more than a minute at a time because by that point the system was almost certainly throttling itself down to remain cool.

Thermal paste CANNOT make a fan not run. You need to figure out the problem with the fan before you worry about ANYTHING else.
 
Dec 15, 2019
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I tried a different fan but the red troubleshooting light cpu led still goes off. It's an asus z97 pro gamer. should be noted the back up fan was kinda broken though so I had to keep it pushed in with my finger while I turned it on.
 
Dec 15, 2019
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Yes yes it did. should be noted my water cooler has a water cooler and then a brass fan. the secondary brass fan was not spinning with it. but this backup fan spinned when plugged into both places.
 
Dec 15, 2019
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He was sure it was the fan but I tried a backup heat synk and it did the same thing. One guy thought it was thermal paste. I'll save that one for last. I'm noticing I may have gotten a tiny bit on the motherboard. I may need to put the glasses cleaner on a cloth and whip it off.
 

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