Does screw over tight decrease the efficiency of cooler?

[Lugia0529]

Hi all, I have a question about the screw of the cooler.

For example, a cooler master cooler have 4 screw to make it fixed on the board. During the installation of cooler, I always tightening the screw until it cannot be tighten anymore.

My problem is, does the screw over tight? If it is over tight, then will screw over tight decrease the efficiency of the cooler?

 

Hope you all know what i'm saying

 

Thanks in advance.

[El_Capitan]

Yes. If the surface between the CPU and the heatsink is too perfect, or has some bumps, then it will squeeze out too much of the thermal compound applied to it. The best thing to do is never tighten it where you're using 100% of your strenght to tighen it further. About 40% is good enough.

[Lugia0529]

So I need to reinstall the cooler? Does it cause a great decrease in the efficiency of the cooler?

[El_Capitan]

Depends on how much thermal compound is still between the heatsink and cpu. Have you tested your system and gathered temp readings? If the temps get too high, I'd think about re-installing, otherwise you might still be okay. Some heatsinks have springs/spacers to prevent you from overtightening, but I'm not sure if you have those on the heatsink you have.

Edited September 24, 2010 by El_Capitan

[RJR]

If the surface between the CPU and the heatsink is too perfect, or has some bumps, then it will squeeze out too much of the thermal compound applied to it.

The thermal paste is designed to fill microscopic imperfections in the heat sink and CPU IHS, the more that squeezes out because the surfaces mate together tightly is a GOOD thing, not bad. You want the least amount of TIM possible.

[El_Capitan]

The thermal paste is designed to fill microscopic imperfections in the heat sink and CPU IHS, the more that squeezes out because the surfaces mate together tightly is a GOOD thing, not bad. You want the least amount of TIM possible.

Not unless you squeeze out everything. I've had that happen before and got temps in the 60's idle on an i7 920 d0 when otherwise it was in the 40's idle on stock voltage. All I did differently was tighten it less. You want an even layer, definitely not a glob, but not so little that there isn't even any coverage in certain areas.

[TheHippi]

Not unless you squeeze out everything. I've had that happen before and got temps in the 60's idle on an i7 920 d0 when otherwise it was in the 40's idle on stock voltage. All I did differently was tighten it less. You want an even layer, definitely not a glob, but not so little that there isn't even any coverage in certain areas.

Um, if you tighten it so much that you squeeze out all of it, that basically means that there are no spaces for it to fill. Which means that you shouldn't need any TIM. Unless you overtighten it so much that you warp the heatsink base.

[RJR]

Not unless you squeeze out everything. I've had that happen before and got temps in the 60's idle on an i7 920 d0 when otherwise it was in the 40's idle on stock voltage. All I did differently was tighten it less. You want an even layer, definitely not a glob, but not so little that there isn't even any coverage in certain areas.

It sounds like you either had large imperfections in one of the mating surfaces or user error when tightening down the heat sink.

 

You can take a known straight edge to determine if either surface is concave or convex and then lap the given surface to take care of the problem, also criss cross pattern when tightening.

[El_Capitan]

It sounds like you either had large imperfections in one of the mating surfaces or user error when tightening down the heat sink.

 

You can take a known straight edge to determine if either surface is concave or convex and then lap the given surface to take care of the problem, also criss cross pattern when tightening.

Always a possibility, but I've built quite a number of systems (not sure if I've built a hundred yet, but probably at least 50 in my lifetime), including multiple different heatsinks and cpu's. I've only lapped surfaces a few times (like 4-5 times), but the time it took to do it wasn't worth the time, imo. The right application of thermal compound and attaching and tightening the heatsink properly is usually enough to do the trick.

[Locutus]

Not unless you squeeze out everything. I've had that happen before and got temps in the 60's idle on an i7 920 d0 when otherwise it was in the 40's idle on stock voltage. All I did differently was tighten it less. You want an even layer, definitely not a glob, but not so little that there isn't even any coverage in certain areas.

You probably put way too much TIM on.

 

Usually a very small amount will do. For example, I put about half the amount of a pea on my heatsink, tightened it all the way down and it was perfect.

[Waco]

The right application of thermal compound and attaching and tightening the heatsink properly is usually enough to do the trick.

I dropped my CPU temps by well over 10 C by lapping the base of my cooler and the IHS on my CPU. It's almost never *not* worth it to lap as long as you don't care about the warranty on your parts (for coolers it's nearly useless, for CPUs I guess you could argue that it's worthwhile to keep your warranty).

 

As far as over-tightening a heatsink - it's always a GOOD thing to get rid of extra TIM as long as you don't warp the cooler, board, or damage the CPU socket. Most coolers with screws that bottom out are pretty much designed to be tightened to that point.

Edited September 25, 2010 by Waco

[Lugia0529]

Just reinstall the cooler and there is no big change on the temperature, only about 1~2 degree lower than before.

The temperature when i am on folding@home is about 48~50 degree on AMD Phenom II X4 955 CPU, is this temperature still in acceptable range?