Cleaned parts in computer, now fan(s) go crazy every minute or so.

[RookiePresent]

I just cleaned out the heat sink in my computer because there was dust packed in there. I got it all back together and running but now every minute or so the fan(s) will get really loud and spin really fast. I googled it, and it said it was because it was dirty. I just cleaned it, but not the whole computer but this probably only arose after I put it all back together.

Is it even a problem? I got a CPU thermometer app and it says my CPU is running at ~43C.

My computer is an HP Envy h8-1534.

 

[rieverjohn]

Did you remove the cooling fan and heat sink when you cleaned your computer? If so you may need to apply new heat compound between CPU and heatsink. If you didn't remove the heatsink could you have knocked it and destroyed the seal so you may need to renew the seal compound anyway.

 

[RookiePresent]

Did you remove the cooling fan and heat sink when you cleaned your computer? If so you may need to apply new heat compound between CPU and heatsink. If you didn't remove the heatsink could you have knocked it and destroyed the seal so you may need to renew the seal compound anyway.

Yes, removed the fan and heat sink completely, and removed the fan from the heat sink and heat sink from the board behind it. Is the seal on that square copper contact plate that's on the back of the heat sink?

 

[rieverjohn]

Did you remove the cooling fan and heat sink when you cleaned your computer? If so you may need to apply new heat compound between CPU and heatsink. If you didn't remove the heatsink could you have knocked it and destroyed the seal so you may need to renew the seal compound anyway.

Yes, removed the fan and heat sink completely, and removed the fan from the heat sink and heat sink from the board behind it. Is the seal on that square copper contact plate that's on the back of the heat sink?

 

[rieverjohn]

Hi Rookie, I have had a similar problem, if the heatsink isn't perfectly seated on top of the CPU and without a good film of heat dissipation compound then the CPU can overheat only slightly causing the fan to speed up and cool the CPU to acceptable level, fan slows down and CPU heats up again causing the cycle to repeat.
Maybe saying "seal" wasn't the best description, the heat sink must be flush with the CPU, if the heatsink isn't seated properly it doesn't do its job.

 

[RookiePresent]

Hi Rookie, I have had a similar problem, if the heatsink isn't perfectly seated on top of the CPU and without a good film of heat dissipation compound then the CPU can overheat only slightly causing the fan to speed up and cool the CPU to acceptable level, fan slows down and CPU heats up again causing the cycle to repeat.
Maybe saying "seal" wasn't the best description, the heat sink must be flush with the CPU, if the heatsink isn't seated properly it doesn't do its job.

How do I check that the seal is good? The contact plates are in the back of the computer, so I have no way of knowing how well the contact is because it's hard to see. I didn't use any sealing compound, just took it off and back on. I'll need to buy some.

 

[rieverjohn]

Hi nightowl, yes you must buy that compound. The heat sink fan/assembly is usually mounted with spring loaded screws at the corners, or a clamp arrangement, so it should really seat itself, but you do need that compound beetween CPU and heatsink.

 

[RookiePresent]

Hi nightowl, yes you must buy that compound. The heat sink fan/assembly is usually mounted with spring loaded screws at the corners, or a clamp arrangement, so it should really seat itself, but you do need that compound beetween CPU and heatsink.

Okay, thank you. I'll buy some and see what happens. Do you know what it's called/ where I can buy some?

 

[Paperdoc]

It's called thermal paste for a CPU. A small amount of this stuff is placed between the top surface of the CPU case and the flat bottom plate of the heatsink. It increases the rate of heat flow from CPU to heatsink. Too little is not good, but too much (a thick layer) also is not good.

You need to check for instructions on cleaning off any old thermal paste. You'll have to remove the heatsink again and examine its surface and that of the CPU top. They need to be cleaned of old paste - often with a LITTLE bit of a solvent like rubbing alcohol on a tissue - so the surfaces are smooth and free of old residue. Then READ the instructions on how much thermal paste to apply, and how. Often these depend on exactly which CPU you have (because they vary in surface area). Good instructions often are posted on the website of the paste's maker. Apply just the right amount of paste, then re-mount the heatsink on the CPU (sometimes the instructions advise a small twisting motion) and tighten it down again. Just replacing this paste properly should improve heat removal, but there will be a small further improvement over the first couple of weeks after the job is done.

For reference the next time:
Usually you do not need to replace the thermal paste IF you do NOT remove the heatsink from the CPU. So next time, just unscrew the fan from the heatsink and clean, then replace it.

 

[rieverjohn]

Just a thought on how I clean out a PC, I have a small cylinder vacuum cleaner with a hose that I can plug in either to suck or blow. Blowing dust out does an adequate job if done regularly, it's surprising how much dust is attracted to electronic part via static.

rieverjohn

 

[RookiePresent]

It's called thermal paste for a CPU. A small amount of this stuff is placed between the top surface of the CPU case and the flat bottom plate of the heatsink. It increases the rate of heat flow from CPU to heatsink. Too little is not good, but too much (a thick layer) also is not good.

You need to check for instructions on cleaning off any old thermal paste. You'll have to remove the heatsink again and examine its surface and that of the CPU top. They need to be cleaned of old paste - often with a LITTLE bit of a solvent like rubbing alcohol on a tissue - so the surfaces are smooth and free of old residue. Then READ the instructions on how much thermal paste to apply, and how. Often these depend on exactly which CPU you have (because they vary in surface area). Good instructions often are posted on the website of the paste's maker. Apply just the right amount of paste, then re-mount the heatsink on the CPU (sometimes the instructions advise a small twisting motion) and tighten it down again. Just replacing this paste properly should improve heat removal, but there will be a small further improvement over the first couple of weeks after the job is done.

For reference the next time:
Usually you do not need to replace the thermal paste IF you do NOT remove the heatsink from the CPU. So next time, just unscrew the fan from the heatsink and clean, then replace it.

Thank you both for the help. I'll try to get some paste and do as the instructions say. It will be while until I can see if it will work for sure, but it's looking good so we'll call it solved.