Discussion in 'Article Discussion' started by bit-tech, 7 Apr 2020.
I assume they aren't using aluminium cold plates in their laptop coolers then?
I wonder why all laptop manufacturers don't use this if has such a good effect on cooling?
Does it have a limited lifespan that would reduce the life of the laptop?
I doubt that. It's probably more because it dries out. Quite quickly too.
So 2 months after you purchase it you'll have to open it and reapply? Will you lose warranty?
From my experience of liquid metals, yes, it does 'dry out' but retains its full effectiveness for at least 3 years (the longest time I had some in regular use).
The thing with laptop coolers, and I'm paraphrasing der8oring on his Asus Zephyrus 14 review, is that contrary to desktop coolers, they are not nickel plated, and so leave the liquid metal long enough (2+ months) and it'll fuse with or even consume the cooler.
I'd take a picture of what happened to my laptop's cooler after a year but I need it to hold on a little while longer so I'd rather not open it up again.
I've used it on nickel to nickel, copper to nickel and copper to bare die. All of them 'fused' (I like your name for it) and the copper to nickel in particular took a fair bit of force to separate. All retained full effectiveness although only the copper to bare die was in use for 3 years. Usually it was on for no more than 12 months.
I used 3 different manufacturers which included Phobya, Cool Lab and one I can't remember.
I only stopped using it when I fitted a i7 990X and didn't want to lap it when I finally removed it. I found that lapping both the waterblock and CPU was the only way to totally remove it.
If you use Liquid Metal on Aluminium it will eat it away in minutes not months.
Two issues: mechanical cycling and thermal cycling.
Laptops flex, a LOT. Even the most rigid-feeling Apple fondleslab is internally squishing about if you torque it even a surprisingly little amount (e.g. grab the edge protruding from the laptop sleeve and slide it out while compensating for the weight transferring to one hand, and you are applying a significant torque as well as off-axis point-loading). Even sitting the laptop on an uneven surface and leaning your palms on it will apply a surprisingly high force even for only a small displacement. Thermal cycling is similar, but the displacements are smaller and the forces MUCH larger (easily tens to hundreds of kg for rapidly heating CPUs and GPUs).
The upshot of these effects is the HSF assembly and the CPU/GPU die surface are regularly displaced laterally and vertically with high force.
With 'grease' type compound this is dealt with by the compound being a 'thick' squishy slab that can squeeze out of the way and then flow back in, at least for a few years until the volatiles evaporate (even then, the remaining thick paste is perfectly adequate until you remove it and try and remount without reapplying). Or you use a thermal pad, which is less efficient thermally but has several decades of useful life.
With 'liquid metal', you don't have that squidgy leeway. If it doesn't eutectically bond, you have an extremely thin layer which can seperate and introduce air bubbles on recontact (introducing hotspots over the die). If it does bond, then you have nice thermal conductivity but are now transferring those mechanical loads to the solder microbumps between the die and the substrate, which can go very badly indeed (e.g. the multiple generations of Macbook Pro vulnerable to solder cracking under the GPU).
If you buy a gaming laptop and expect it to last a generation before replacing it with the New Hotness, it's likely not an issue. A few years down the line, after the warranty has expired, maybe not so great.
I am thinking of buying a new one, thank you for sharing your experience of having a laptop cooler.
I wonder if any manufacturers will start to use those graphite pads that Custom PC reviewed a year or so ago. They looked very promising
They work well enough - I have one in my spare/test PC to save on endlessly replacing the TIM.
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