THE LUNCHBOX

Removing Your Integrated Heat Spreader

By: Haut^Karl

Tuesday, October 8, 2002

So your a mad overclocker and you want to remove that Integrated Heat Spreader(IHS) because it may drop your temperatures that few degrees you need to gain perfect stability? Not a bad idea if you have the skills to remove the IHS and you have the correct type of heatsink.

"What? I'm gonna rip that stupid thing off and slap my favorite heatsink on there and I'm gonna be fine," says Bob McHasty. Some people have tried this and have put the IHS *back on* since they obtained strange results and they chipped the corner off the core. Let's take a look at why the above scenario is a bad idea.

First, the IHS is installed to "spread" the heat generated by the core across a larger surface area as fast as possible. McHasty's first problem was that he did not take into account the IHS is made of copper. Copper conducts heat about 2.5x better than aluminum. "But my Pentium3 doesn't have a heat spreader." That's because the Pentium3 core has almost 28% more surface area but only produces 12% more heat. The internal design of these cpus has stayed roughly the same but the process to "etch" them into silicon has shrunk from 180nm to 130nm. Unfortunately, the current consumed does not shrink by the same ratio.

Processor

Speed(GHz)

Heat(in watts)

Surface Area(mm2)

Pentium3 EB 256k cache

1.1

33.0

106

Pentium3 Tualatin 256k cache

1.13

29.1

~76

Pentium3 Tualatin 512k cache

1.13

28.7

79

Celeron Tualatin 256k cache

1.1

28.9

~76

Now, we have to dissipate marginally less heat thru a significantly smaller junction. Aluminum can no longer support a suitable junction temperature for the cpu to operate normally. The heat the cpu pumps into the aluminum heatsink cannot dissipate fast enough. We have to resort to copper to obtain the junction characteristics we require.

So what does this mean? This means that copper has to be the first material the cpu pumps heat into. Intel chose to glue the copper directly to the cpu in the form of an IHS while AMD did the reverse. AMD provides with its shrunk down Athlon XP an aluminum heatsink with a copper base plate integrated into the bottom of the heatsink.

So which method is better? We believe the better performing method is to have a copper base plate welded to the base of an aluminum heatsink(Of course an all copper heatsink would be ideal). For instance, the Thermalright AX-7. This will reduce the number of weak junctions to one. The thermal pad Intel uses underneath the heatspreader is long-lasting, easy to apply but performs worse than thermal grease. The thermal pad plus the grease you apply to your Tualeron makes 2 weak junctions that hinder the dissipation of heat. This email from Van's Hardware to Nevin House, Artic Silver Inc illustrates what effect junction size and thermal grease have on temperatures(Pay attention to the blue text).

So that's the heatsink problem out of the way. Second, the IHS has thickness which when removed will reduce the spring tension provided by the retaining clip. Somewhere on Intel's site you can find an article about thickness of thermal paste & retention clip strength and their relationship to conducting heat. If I recall correctly, 10 lbs of force was the recommended strength of the clip. If you have a heatsink with a copper base plate designed for a Pentium3 or AMD Athlon then use it. Pentium3s, Athlons and Tualerons without an IHS are similar thicknesses.

For some reason you have a heatsink that doesn't provide enough pressure on the cpu but you would like to use it. The quick and easy way to overcome this is to pull apart the heatsink and glue a shim underneath the point where the clip pivots on the heatsink. According to Intel's pdf, the IHS has a thickness of 1.6mm. You can add a thicker shim for more force or vice versa.

Lastly, the Tualeron core is more fragile than that of a Pentium3 so be careful not to smash the corners off the core. Add some foam/neoprene "dots" to the 4 corners of the cpu substrate to stabilize the heatsink during installation and removal. This funky foam shim can be purchased from this site.

An alternative would be double sided foam tape. You can purchase it at drug stores and art supply places. Leave the non-adhesive paper on one side of the tape and cut out 4 small squares. Stick them on the corners of the cpu substrate but *don't* remove the non-stick paper. Otherwise your heatsink will be stuck to the cpu with double stick tape!

To remove the IHS from the cpu substrate, you can pry it off or try some acetone(nail polish). To pry it off, place a credit card along the edge of the IHS in order to protect the cpu substrate. Do not damage the substrate as it conatins the microfine traces that connect to the 370 pins underneath. Poke a corner of a small screwdriver under the edge of the IHS while resting on the credit card. Gently pry the IHS upward a little. Rotate the cpu 90 degrees and do the same thing. Keep prying then rotating till the IHS falls off. Take your time and be careful.

Use some decent thermal grease as the poor quality silicone greases will seperate leaving dry mud underneath your cpu and silicone all over the top of your cpu. I have used Arctic Silver III but I cannot say I noticed enough of a difference to warrant paying $6 for 3 grams. Stack 3 pennies on top of each other and that's about the same volume of AS3 you will get.

We will provide some temperature results when we are ready to permanently install our Tualeron. No need risking a cracked corner and dead cpu while we hack at some more slotkets. If you put together some data before and after you remove yours, send it to us and we would be happy to add it to this article.

 

DISCLAIMER: These mods will void your warranty. Do not attempt any of these if you fear you will not be successful.

We accept no responsibility for your errors, loss of hardware, software, data, or anything else for that matter.

2002 The LunchBox