Roundup with 5 phase change pads: Honeywell PTM7950, PTM7950SP, OEM PCM5000, PCM8500 and Thermalright Heilos Review

1 - Introduction an product overview 2 - Test methods and equipment 3 - Thermal resistance, mimal bondline thickness 4 - Thermal conductivity, CPU and GPU simulations 5 - Microscopy and laser-induced breakdown spectroscopy 6 - Summary and conclusion

1. 1st place Honeywell PTM7950

This pad is today’s test winner. However, it is always difficult to find an original. This PTM lasts much longer than most pastes on the market, but it is not infallible either. After several thousand cycles, the PTM tends to become crumbly and cracked, but this is almost negligible in relation to the normal application time of a consumer, as this could only be achieved after several years. The pad is only available in 0.25 mm thickness, while many imitators use 0.2 mm. However, this is NOT an original PTM7950.

2. Place: PCM8500 OEM

The OEM pad does not quite come close to the PTM7950, but is a very good alternative below 200 µm. I assume that some of the “PTM7950” with a thickness of 0.2 mm on the relevant online platforms are something similar. The performance is good and if the price is right, you can really go for it. So it doesn’t always have to be “Honeywell” (which it usually isn’t), even if it says so. I have already written a test on the Burn-In and the differences (link on the first page) and compared both pads in great detail. This also makes it clear which was the second pad in this older test.

3. Place: Thermalright Heilos

Yes, you are selling a kind of original here (which can even be checked via the code), but in the end Thermalright is also just buying. You get a PTM pad, which is positioned between the PCM5000 and PCM8500 OEM pads in terms of performance and tends towards the performance of today’s loser. Yes, it works, but you have to be sure that you can achieve layer thicknesses of less than 175 µm, better 150 µm, otherwise the pad has too little contact for a clean burn-in. You can use the pad and below 50 µm you will definitely get there, but unfortunately it’s not really great.

4. 1st place: Honeywell PTM7950SP

It is more or less the paste for the pad but by far not as powerful as the pad. But you can use it if necessary if the IHS of the CPU is severely bent. For me, however, it’s only good enough for penultimate place today, even if it would actually have been last place based on the thermal resistance. However, the paste saves itself by being more universally usable and less stressful to apply, because the loser of the day is far too crumbly.

Warning! However, I strongly warn against the idea of using this paste as a putty replacement on VRM or memory modules, as it sticks quite well when solid. If you then remove the cooler, you have lost out and, with a bit of bad luck, will tear the components off the board at the same time. So please don’t do it!

5. Place: PCM5000 OEM

This pad does what it is supposed to do, but it doesn’t do it particularly well. You can recognize it by its rather dark color and very brittle consistency. You can recognize it even without a microscope with a simple magnifying glass, because these streaks and dark speckles cannot be found on any of the other pads tested. The PCM5000 costs less than half the price of the PCM8500 and unfortunately you can tell. Anyone who gets their hands on a darker, crumbly pad should be warned.

Summary and conclusion

I don’t want to be the judge of copycat products, but what is good is unfortunately copied all the more. The PTM7950 is the test winner, but it is only the original. For this very reason, I will test other products from more trustworthy sources, where you can be sure of what you are actually getting. In this context, I also refer you to the forum thread with the user test, because the first results of the readers should also be available here in the foreseeable future.

The PCM8500 as an OEM product is a very positive surprise, as it comes quite close to the PTM7950. What is a bit of a problem here is the higher pressure required for thin layers. And I can’t think of a reputable source where you can get it labeled and with a guarantee of origin. Incidentally, the Thermalright Helios is a disappointment from my point of view, because it is worse than printed. Yes, you can use it and will certainly be able to achieve useful results, but the optimum unfortunately looks different.

I can only advise against the PCM5000, the dark pad is not something you should bother with. The 7950SP PTM paste from Honeywell is also not what I would necessarily prefer. It can be used in difficult cases, but a good paste is much better and makes more sense. I will now try to retest the PTM pads available from reputable suppliers (Thermal Grizzly, Gelid, X-Apply etc.) but that will take at least a little time. But I have already planned a separate section for PTM in the upcoming database. Pastes, PTM, Putty and Sheets will then be searchable and comparable separately. I am currently on test object 26 and will certainly test another 10 to 15 pastes before I can go online with the database. Otherwise it would be pointless.

However, I would like to take this opportunity to reiterate my request for more pastes, pads and putties, as the selection and stock can never be large enough. However, please discuss these things in advance via PN to avoid duplicates!