I noticed that the temperatures on my Intel Ultra 9 285H kept jumping to 105°C, which caused the CPU to Throttle and sit at around 35W even under heavy workloads (e.g. Cinebench26). 35W on this CPU can be perfectly fine because it's very efficient, but of course this severely limits Turbo Boost, and when you rely on a lot of performance (e.g. rendering), you really notice it. Besides, the 285H shouldn't be sitting at 105°C on the E-cores while only drawing 35W, to begin with.
I decided to replace the liquid metal on the CPU with a graphene pad (for best thermal conductivity), and the old thermal paste on the GPU (NVIDIA RTX 5070 Ti) with a phase transition (PTM) pad. For all the remaining components, I bought thermal putty – everything from Thermal Grizzly (all from Amazon)
- Thermal Grizzly Kryosheet
- Thermal Grizzly PTM Sheet
- Thermal Grizzly Putty Pro
Before the rebuild, I ran a Cinebench 26 benchmark – Multi-Core, Single-Core, and Multi-Core again – plus FurMark, so the graphics card would also be at its thermal limit (i.e. the laptop's cooling system fully saturated).
For the rebuild itself, I mostly followed this video, it helped me a lot:
https://www.youtube.com/watch?v=1gPEDmaWAlM
It's not exactly my model (possibly the RTX 5080 version), but it seemed perfect for reference.
Important note about the liquid metal and the graphene sheet:
Both are electrically conductive and must therefore NEVER come into contact with the motherboard or other components – the only exceptions being the CPU itself and the orange insulated area around it.
And disconnect the battery and hold the power button for 15 seconds!
I first removed the liquid metal from the heatsink, then from the CPU, as thoroughly as I could. What remained was a dried-up residue (apparently the main reason for the overheating and throttling).
For this I had bought lint-free cotton swabs and lint-free cloths (also from Amazon).
Then I cleaned the motherboard, and the GPU last.
A plastic tool works well for scraping things off – never use metal.
Everything dissolves and comes off with 99.9% isopropyl alcohol.
The old green thermal putty stuff, however, was a pain to remove, and residue remained all over the motherboard – which isn't too much of a big deal, since it's not conductive.
Then came the question of how to get the CPU and the heatsink free of the dry liquid metal residue, because the Kryosheet is only 0.2mm thick and therefore can't compensate for unevenness, unlike PTM sheets.
Some research showed that you can polish the CPU and the contact surface with thermal paste, since it dissolves the liquid metal residue and definitely won't scratch or damage the CPU.
I found some MX-4 in my drawer and gave it a try. It took a long time and I went through countless rounds, but it worked – in the end almost nothing was left, and the die and the contact surface felt smooth to the touch.
After that, I applied the TG PTM Sheet to the GPU – I had stored it in the fridge beforehand and then cut it to size with scissors.
Next, I distributed the Thermal Putty Pro over the voltage converters and RAM chips. That was just as exhausting and time-consuming as shown in the video. At some point I simplified things a bit by rolling the putty on the silicone mat into a long thin roll, letting me cut off little slices, or laying a longer piece across a row of components and then flattening it with the included spatulas.
Finally, the Kryosheet went on. I didn't need the included insulation film, since the CPU already has its own insulation layer. I had bought a 25x25 graphene pad and then cut it so that it definitely overlaps a bit – not too small and making sure the CPU die is fully covered. The included silicone oil works surprisingly well: the sheet could be positioned nicely but still adhered to the CPU.
Then the heatsink went back on. Of course I used the opportunity to clean out all the dust, but there really wasn't much to begin with.
When tightening the screws, pay attention to the correct order and listen for the clicking sound, as described in the video.
When I had put everything back together, I wanted to test whether it worked – and I first had a small heart attack, because the laptop showed absolutely no signs of life. But I guess because the battery was disconnected, it was set into shipping mode or something, and it seems you first have to plug it into the charger and hold the power button for a while for it to boot, and then it takes a moment until you finally see the Windows login screen.
Then came the tests, and I was so glad I went through all of this!
The CPU never went above 100°C anymore, and the CPU cores stayed evenly warm – no more hotspots! The Cinebench Multi-Core score was 1200 points better! +35% performance! The CPU was now drawing a constant 85W because it no longer had to thermal throttle.
The combined test with FurMark running in parallel didn't score much higher, because the laptop had simply hit its maximum power draw – but now at normal temperatures.
Now, a few days later, I can say that the laptop also runs cooler in silent mode (configured via G-Helper).
The GPU temperatures stayed roughly the same, but they were absolutely fine before. The PTM sheet is better than the old thermal paste (and will improve slightly), but since the CPU is now conducting more waste heat into the cooling system, the overall system gets slightly warmer – which doesn't result in any change for the GPU, I guess.
