Liquid metal experience (didn't went as expected)

So i gotta admit, I was not expecting this result at all.

I was working on my P157SM and applied the LM carefully on both my GPU and CPU, small layer on the die's and then on the heatsink.

I saw a much lower idle temperature on my CPU and started a benchmark to see if I can finally dream of 80c on my notebook. To my suprise I saw that the system ran more stable and it took longer, BUT the system was still at 91c on load. Now the thing is, my CPU heatsink is actually copper and the fins on the end are all aluminium. When tested without before applying the LM the CPU would become hot, but the copper plate and the pipes would not really get hot and the exhaust not really hot either. After 5 minutes of 91c I could still touch the heatpipes and not feel to hot, so I know that there was an issue.

After applying the LM, I did the same, tried to touch the heatpipes and they were noticeably hotter, I could barely touch them, but the aluminium fins, where really bad at absorbing the heat and failed to spread it, so basicially the CPU would start heating up because the aluminium just doesn't get hot enough I think.

So I had a sad face and removed the LM from my CPU and Heatsink, I had to use Coolab metal wool and I had to scratch it off. Applied normal thermal paste and ran the Benchmark again.....after 3 minutes when the CPU should have been 91c, it was on 84c, slowly going to 91c after a bit more time.

I quickly realized, that I basicially had done a very rough lapping job on the heatsink and that actually helped drasticly, it was downright scary how much it improved on temp stability.

Now to the GPU, when i started 3dmark, the temps would instantly shoot up to 95c and beyond if I hadn't stopped it. So i reopened to case and noticed, that the liquid metal was probably to thin, so I applied more and....
Whoops, I pressed to hard on the tube and easily dropped 1/3 of the entire metal on the die... It was shiny liquid metal alright, but then I decided to put on the heatsink to see how it would spread, since the CPU had improved so much, maybe there was the same issue with the heatsink not being even. Well no, the heatsink still didn't connect with the die, and there was only 1 tiny drop of liquid metal on the heatsink that barely connected. At that point I did the "rough lapping" again, cleaned everything up again. This time I used my normal thermal compound again, this time however I would be VERY generous with the paste and just smack it on to the die and heatsink, after that I did benchmark my GTX 970m, which ran on stock @ 66c, which was insane for me, normally the temp would hover around 70s.

So In the end, the liquid metal didn't improve my temps by being the liquid metal itself, but rather forcing me to notice, that my cooling system itself had entirely different flaws I should adress first. After this I realized how important lapping actually is and how important it is that your cooling system doesn't leave airholes I will now always recommend doing lapping. I already bought a full Copper CPU heatsink and I will mod my GPU heatsink so it fits perfecly on the die.

I'm pretty sure I won't have to use LM anymore to achieve my desired temps, I'll probably use the LM for other projects and run my current notebook with kryonaut instead, as far as I see things, I'm pretty sure kryonaut will keep my system at 80c on stresstest and on normal use around high 60s - 70s.

I'll keep you guys updated. I should get my new heatsink around 13th - 15th september

TL R:
Before thinking of high quality thermal compound, make sure your cooling system is flawless itself first.

 

Liquid metal does not really good contact to be worth it, it's true. Also it's generally a bad idea to let the heatsink spread the liquid metal as it could escape doing that.

 

I did that experiment because of the strange behaivior with the first time when I made thin layers on the heatsink and the GPU to figure out where the heatsink would actually touch the die, only to realize that the heatsink doesn't even remotely get close to the die. Which baffles me to no end, the huge gap between heatsink and GPU, still having mid 60s degrees on a GTX 970M with normal paste is insane, once I get that thing to actually touch the die, the temps will probably drop down even further.

 

You can suck the LM right back up into the tube no problem.

LM is no good with a heat sink gap. It might look ok with temps straight away, but it will "dry" over time and will lose contact (happened to me), this might cause stability problems as part of the die is uncooled. Or, if the gap is filled with a lot of the stuff the risk is it'll escape when given a sideways bump, though I havent really seen a lot of anecdotes of this happening.

Clean up is isopropyl and absorbent paper towel, I've never had to scratch anything off a die, it alloys into the heatsink where its applied but thats no biggy, I'll just sand it off the 980M heatsinks that have been apart for 4 months now

LM is for heat transfer. If your aluminium fins cant get rid of the heat fast enough, it'll all get just as crazy hot in the end.

If your CPU says 90C, and youre not burning your fingers on the heat pipes and the fin grilles, there is something not right with either the core/heatplate contact, or the heatsink.

 

You can use the fully copper heatsink from the 17 inch series IIRC.

 

It's already ordered

Exacly, when applying the LM,the heatpipes were so hot I couldn't touch em, but when touching the aluminium fins, it was warm but not hot, it's as you said, in my case the Liquid metal didn't do much due to the aluminium fins, it basicially fails completely at the heat transfer from the heatpipes to the fins, which causes the heatpipes to get really warm and save heat.

Also it wasn't difficult to get the LM off the die's but it was hard to get from the copper heatsinks. I mean not the LM itself, but the resedue it leaves behind, well... I guess hard isn't the right word, scratching a bit with the included wool removed it easily, but it's more effort than normal thermal compound.

As I said, even tho I couldn't use liquid metal due to flaws in the heatsinks themselves, it did help me figure out how terrible my cooling system actually was. I mean the GPU heatsink didn't fit at all, I couldn't get the plate to contact the GPU die at all, it would only touch the center a little bit and that's it. After some lapping I expect great results especially from the GPU due to the fit being insanely bad. I've never thought, that my entire cooling system was actually this bad due to terrible die contacts. I have no idea how my GPU can run on mid 65s to low 70s with normal thermal compound.

 

Note that heatpipes will often feel hotter than the fins due to the physics of what is going on.

 

I know, but when the CPU is running on 91c for 5mins straight and you can still touch the fins and keep your finger on it, then you know that there is something terribly wrong.

 

It might be there is something up with your heatsink then as aluminium is not that much worse than copper.