Buying cheap crap from Amazon and it not working as expected? - You don't say! 🤣

For heatsinks, I always check their bottom for pits/bumps with a new knife blade that I only keep for this particular purpose.

Thermal tape is always a big NO-NO for me. In addition to poor conductivity, I avoid it for the reasons mentioned above - you just never know when and how it will fail. I only make exceptions when it's the original stuff on the chipset heatsinks of old motherboards.
Thermal glue is indeed the better way to go. But like most cheap stuff these days, if it's from [sc]amazon or similar China e-mall, it's probably best to try it on hardware you don't care about (as much) before trying it on anything expensive. While I have not heard of complaints of thermal glue letting go of whatever it was supposed to hold, I still think it's worth testing every new batch you get, as you never know when some cheap manufacturer might have changed something in the formula or goofed up.

Gluing on low quality heatsinks doesn't sound great. In fact I don't see how the tape was the problem. Verify the heatsink contact pattern and use quality tape, the next person will want to take the heatsinks off.

One more thing to watch for when getting cheap, generic heatsinks: Once I bought supposedly the "good ones", advertised having 3M thermally conductive tape. The paper to peel had 3M's product code on it and when I looked it up, it was not thermally conductive but just a simple double-sided adhesive tape.

I don't know to what extent a piece of aluminum, even if it is an alloy or something similar, can be considered poor quality. What I never do is use thermal tape to attach large heat sinks, only small ones for RAM chips or MOSFETs. I also always sand the heat sinks before using them.

I always use cheap heatsink from China with my own quality tape or pads of different thickness or Paste. Never had Contact Problems.

I use Deepcool Z5 paste in the middle (not Kryonaut as it's not as long term stable, Arctic MX is also good) and a small dab of CA glue in the corners to attach heatsinks. If I need to remove them I dissolve the CA glue with acetone.

This has been a thing for many decades. If you don't believe me, pull that green aluminum heatsink off your northbridge on a 440BX chipset motherboard. It may or may not be flat enough to make contact with the whole surface. If you want something that is properly surfaced, you have to pay up or do it yourself.

With that said, I don't think it's worth fussing over. Yes, it's the case that thermal transfer is impaired if you don't have TIM+sink making full surface contact. But it's also that case that on a chip that doesn't even have a factory heatsink, there's a level of good enough. Portions of the plastic chip package that are in contact with the heatsink will wick heat from adjacent hot packaging.

smtkr wrote on 2025-11-09, 15:18:

This has been a thing for many decades. If you don't believe me, pull that green aluminum heatsink off your northbridge on a 440BX chipset motherboard. It may or may not be flat enough to make contact with the whole surface. If you want something that is properly surfaced, you have to pay up or do it yourself.

With that said, I don't think it's worth fussing over. Yes, it's the case that thermal transfer is impaired if you don't have TIM+sink making full surface contact. But it's also that case that on a chip that doesn't even have a factory heatsink, there's a level of good enough. Portions of the plastic chip package that are in contact with the heatsink will wick heat from adjacent hot packaging.

Is it not worse to have a heatsink not touching the hottest part of the chip than to have no heatsink at all? I feel like at least with no heatsink you get some convection and air flowing directly over the chip. The situation I was having left a .2mm “blanket” of air over the die.

I feel like it would actually make the chip hotter than no heatsink at all.

I've used heatsinks from amazon for various applications without issue (including directly on processors). They definitely do conduct heat in my experience as is evident by how hot the heatsinks get.

To really determine the effectiveness (or lack thereof) would need proper testing with thermal measurements.