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Shiny pad on Slot 1 heatsink

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First post, by TheMobRules

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I got a new old stock AOC Slot 1 cooler which came with a pad in the back where the heatsink makes contact with the processor cartridge. But it's not your usual thermal pad/tape or pre-applied paste, it's a shiny foil-like tape:

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I assume it's supposed to work just like any other pad by increasing thermal conductivity and I can just apply paste between it and the cartridge? Or am I missing something here?

Reply 1 of 29, by Horun

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Have seen those many times and yes apply a very thin but uniform thermal paste on it before attaching. They were designed to not need paste but would not recommend using it bare as it is not new (should be near mirror finish if new, yours has scratches)...

Hate posting a reply and then have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. https://archive.org/details/@horun

Reply 2 of 29, by swaaye

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I believe it is a graphite pad. It might still be up to the task.

I actually found one of those between the heatsink of a Core i5 4670 and it was not adequate for that CPU. High temps and throttling there. Replaced it with some paste and temps dropped tremendously. But a Core i5 4670 is a 84 Watt CPU and a Pentium II / III is more like 35W.

Last edited by swaaye on 2020-08-15, 03:35. Edited 1 time in total.

Reply 4 of 29, by swaaye

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Warlord wrote on 2020-08-15, 03:35:

actually thats the thing you are supposed to remove, there is thermal paste behind it.

Nah it would be a plastic covering in that case.

This thing is like one of these.
https://www.innovationcooling.com/products/ic … te-thermal-pad/

Reply 5 of 29, by Warlord

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Intel used to put those on P4 heatsinks, and people didn't remove them before seating them on the cpu and couldn't figure out while the thermally throttled. anyways thers no evidence that sticking aluminum foil between your cpu and heatsink dissipates more heat than just applying some quality thermal paste. I wouldn't use it.

Then again I look at that heat sink and it isn't milled flat and laped.

Reply 7 of 29, by Horun

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Yes to remove it you would need a good box cutter blade and gently try to peel it off, have done it on a few but it always scratches the aluminum HS. Did not know it was graphite based but found it easier to super clean it and apply some good HS goop.

Hate posting a reply and then have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. https://archive.org/details/@horun

Reply 8 of 29, by TheMobRules

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Thanks for the answers. Yeah, I can confirm that it's definitely not intended to be peeled off or anything, so I went with Horun's suggestion and applied a thin layer of paste before attaching it to the processor. We'll see how it performs.

Reply 9 of 29, by Hoping

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That thermal pad has to be removed and the heatsink cleaned, I guess no one wants 20-year-old thermal paste and the thermal conductivity of that aluminum sheet is doubtful.
Also it is seen that it is not smooth.
You have to check the pressure of the heatsink after taking it out by putting the thermal paste, assembling and disassembling it again to check the pressure before using the processor since there is the possibility that it does not press enough and you need a copper pad.

Thats my advice.

Reply 10 of 29, by TheMobRules

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Hoping wrote on 2020-08-15, 08:48:

That thermal pad has to be removed and the heatsink cleaned, I guess no one wants 20-year-old thermal paste and the thermal conductivity of that aluminum sheet is doubtful.

What 20-year old paste are you talking about? This came without any type of paste as shown in the picture I posted...

Hoping wrote on 2020-08-15, 08:48:

You have to check the pressure of the heatsink after taking it out by putting the thermal paste, assembling and disassembling it again to check the pressure before using the processor since there is the possibility that it does not press enough and you need a copper pad.

This heatsink is intended for SECC1 type cartridges where the PCB containing the CPU is completely sealed inside, so the heatsink just presses against the front side of the cartridge, which is metal and acts as a heatspreader for the CPU:

http://www.x86-guide.net/g0b/en/collection/In … pu-no15488.html

Reply 11 of 29, by cyclone3d

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All that is is a square of aluminium tape. Absolutely worthless. Horrible for thermal transfer and it also raises the bulk of the heatsink away from the CPU heatspreader.

Easy way to get it off is to heat up the heatsink with a hair dryer or heat gun and then peel it off. You will need to clean the residual tape aches be off of the heatsink as well.

Citrus based essential oil or even citrus based furniture polish works great for removing sticky stuff like that.

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Reply 12 of 29, by darry

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cyclone3d wrote on 2020-08-15, 17:25:

All that is is a square of aluminium tape. Absolutely worthless. Horrible for thermal transfer and it also raises the bulk of the heatsink away from the CPU heatspreader.

Easy way to get it off is to heat up the heatsink with a hair dryer or heat gun and then peel it off. You will need to clean the residual tape aches be off of the heatsink as well.

Citrus based essential oil or even citrus based furniture polish works great for removing sticky stuff like that.

Lighter fuel is also great for removing adhesives .

Reply 13 of 29, by TheMobRules

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Well, all the different comments sparked my curiosity, so I ran a bunch of tests:

  • With the pad but no thermal paste
  • With the pad and a thin layer of thermal paste
  • Removed the pad, cleaned and added some thermal taste

The tests were carried out on a P2-450 Deschutes, which is the most powerful SECC1 CPU I have (not sure if SECC1 P3 processors exist at all).

The final result was unsurprisingly that there seems to be absolutely no difference, the temps did not vary more than 1 degree C between tests. So there you have it.

Reply 14 of 29, by cyclone3d

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How were you measuring the temp? The Pentium II doesn't have an on-die sensor.

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Reply 15 of 29, by Hoping

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Well, I'm not going to argue about it, after all the processor has a maximum TDP of 37 watts (http://www.cpu-world.com/CPUs/Pentium-I ... 512E).html), and seec heatsinks are usually big .
I have only given my advice.

TheMobRules wrote on 2020-08-15, 16:41:

What 20-year old paste are you talking about? This came without any type of paste as shown in the picture I posted...

The aluminum is glued to the heatsink I was referring to the glue, I did not explain it well.

Reply 16 of 29, by TheMobRules

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I used one of those thermometers with a flat sensor wedged between the processor cartridge and the heatsink and then also measured the temp on the heatsink alone. I was interested in the heat transfer between the metal part of the cartridge and the heatsink since that is what mattered in this case. Now, I don't know how precise it is, it's not professional equipment by any means but my objective was to determine if there were noticeable differences in how "warm" the heatsink gets, not absolute temperatures or measurements of the CPU die.

I think in this case what makes the biggest difference in terms of heat transfer is the contact between the CPU and the metal part of the processor package, while the cartridge-heatsink transfer that is required can be achieved with basic metal to metal contact. Maybe any differences would be more noticeable with CPU that has a higher TDP? The Deschutes is only 27W after all and it doesn't really take a lot of effort to cool it.

Reply 17 of 29, by ykot

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TheMobRules wrote on 2020-08-16, 02:18:

I used one of those thermometers with a flat sensor wedged between the processor cartridge and the heatsink and then also measured the temp on the heatsink alone. I was interested in the heat transfer between the metal part of the cartridge and the heatsink since that is what mattered in this case. Now, I don't know how precise it is, it's not professional equipment by any means but my objective was to determine if there were noticeable differences in how "warm" the heatsink gets, not absolute temperatures or measurements of the CPU die.

Did you measure the time it takes to heat the heatsink from room temperature and operating "stable" temperature? Because there are multiple parameters to watch for (that is, the whole temperature curve), not just some temperature at some random point of time.

I had this aluminium foil (I don't think it's graphite) on my Deschutes P2 as well and several socket 370 heatsinks too, but in practice I've found it not so good for heat transfer. Before removing the foil, you could do a very simple test yourself - disconnect the fan and power up the PC and measure how quickly the external heatsink becomes uncomfortably hot for your hand to touch. Then, remove the foil and instead apply thermal paste, but not just at the place where the foil was, but either at the whole surface or at least in multiple large spots, then repeat the test. This is subjective but very effective test - the difference in heat transfer is so big that you'll notice difference without using a thermometer.

I think this aluminium foil was used not much as a replacement for thermal pad, but as a softer surface to avoid damaging CPU's die, before manufacturers started to use integrated heat spreader (IHS) somewhere around P3/Tualatin time.

Reply 18 of 29, by swaaye

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I found the Intel Thermal Design Guidelines for Pentium II SECC1. It's clear their preferred TIM is paste, but suggest a thermal pad might be adequate too.
http://datasheets.chipdb.org/Intel/x86/Pentiu … II/24333102.PDF

I imagine a pad is the cheapest, easiest cooling option for the assembly line.

Reply 19 of 29, by auron

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ykot wrote on 2020-08-16, 13:42:

I think this aluminium foil was used not much as a replacement for thermal pad, but as a softer surface to avoid damaging CPU's die, before manufacturers started to use integrated heat spreader (IHS) somewhere around P3/Tualatin time.

all klamath and most SECC1 deschutes didn't have exposed dies, it's just the pii 450 that had been moved to flip-chip packaging afaik.

anyway as there's thermal pads now that have been tested on modern 100-200+w CPUs and perform acceptably with those, i really don't see much reason to use messy thermal paste on 30-40w parts.