thermal paste - how much is too much?

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snail

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So I assembled my new pc today....haven't switched it on yet....no time (working). Cut a long story short I put the ultimate thinnest coat of thermal paste on my cpu....literally....so thin you could basically see the the cpu itself. So my brother was assisting me, and he put a blob of thermal paste on the centre of the heatsink (without telling me until it was on). Now would a small blob make a negative difference (considering it would spread out once the heatsink was tightened on correctly) and would it have any negative affect on the temps? I'm not keen on taking it off as it was hard enough getting it onto the motherboard (zalman cnps 12x).
 
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A pea sized blob in the middle is the right amount.

But if the PC does turn off while booting (to prevent over heating) remove and re-apply thermal paste and ensure heatsink is seated correctly.
 
It'll be fine, I used half a tube of paste on system I assembled a few years ago which once left to 'set' was 2mm thick. That system runs perfectly fine, sometimes hits temps as low as 9 degrees celsius.
 
Rickster said:
A pea sized blob in the middle is the right amount.
Click to expand...

I've tried this before and it's not optimal. The paste does not actually spread to cover the entire cpu and actually leaves a pretty thick covering. Best results I've had is to spread it VERY thinly with a credit/bank card.
 
ponder said:
I've tried this before and it's not optimal. The paste does not actually spread to cover the entire cpu and actually leaves a pretty thick covering. Best results I've had is to spread it VERY thinly with a credit/bank card.
Click to expand...

I second this approach. Use the smallest amount in the middle and just spread outwards.
 
The goal of the paste isn't to create a barrier between the cpu and heatsink; it's to smooth out the microfissures that trap air and prevent heat conductivity - because obviously air is a terrible heat conductor. So thin and wide is your best bet.
 
well the idle temps are currently sitting at 24 degrees. motherboard is sitting at 23 degrees. Room temp set at 22 degrees. PS: cpu is i5 3570k @ stock. Idle time was about 40min.
 
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snail said:
well the idle temps are currently sitting at 24 degrees. motherboard is sitting at 23 degrees. Room temp set at 22 degrees. PS: cpu is i5 3570k @ stock. Idle time was about 40min.
Click to expand...

Idle temp is meaningless. You need to stress test it and record the highest temp.
 
Use the pea size amount in the middle method. The pressure that is created when you mount the heatsink spreads the paste out for you.
 
Pea in the middle, turn the cooler 90deg to the right then back to start position and 90deg to the left, bolt on and go. That normally makes a nice even coating that isnt too thick.
 
Cerebus is correct. +1.
Paste is only to fill the microgaps - the optimal is direct metal-to-metal contact. Thermal paste must only fill the air gaps where you don't have direct metal contact. Anything more and you're running hotter than it otherwise could.
 
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