Seems like a lot of work to me. I thought about conductonaut liquid metal since I already have it laying around after delidding my desktop CPU but the stock cooler of the A515-43 is mainly aluminium so that's a big no no. Besides, you run the risk of it seeping out and shorting something on the motherboard that you didn't coat since the laptop is well, portable and supposed to be moved around alot.
All in all, I think for your and your friend's sanity, he should get a real gaming laptop with a dedicated GPU and adequate cooling. Then it might be worth it to try liquid metal on that since it makes sense for high end components. The performance of the 2500U and the 3500U even in the boost window is nothing to write home about.
It was quite a bit of work; fun though. Bought the base laptop(Single ch. RAM, 768p LCD, wimpy cooler that throttled under light load) for less than half market rate because it had some minor cosmetic damage (nail polish remover I think) and the prev. owner thought the touchpad was bad. Specifically went through the effort so a friend of mine could have a truly 'custom' laptop; something we've both long desired.
Additionally, even after all the mods, we couldn't have purchased a laptop for the same money that would deliver the same level or better of SUSTAINED performance. The whole project was <$500, including shipping to him after I built it. Inclu. cooler, an unnecessary touchpad from a Nitro 5 (ooo, red trim, pretty), a wifi antenna I broke and replaced, Secondary SATA SSD, SATA cable, 1080p LCD, dual-ch 16GB RAM, and decorative vinyls.
I did mask the CPU with tape, and then clear nail polish around it. I removed the tape off the die and then applied the liquid metal, spreading it gently with a cotton q-tip using a tapping motion to wet the LM onto both the CPU die and the Cooler. (I used generic Galinstan from eBay, ordered for purpose since I lost my previous vial I got from Latvia) Once 'wetted' to a surface, and as long as there is not an extreme excess, it will not migrate. I think it's Van Der Walls force that keeps it in place, kinda like machinists gauge blocks. (BTW, I have spilled LM on a RAMstick and killed it, you do need to be careful, but it is not THAT bad. As long as it doesn't touch aluminum or get under a BGA component, you can usually clean the board off w/ strong isopropyl and it works A-OK)
The Nitro 5's cooler (AN515-42 OEM Cooling Fan Heatsink AT28X001FA0 DFS541105) is copper baseplated. It's LM TIM safe.
If you don't want to go through the effort of wiring up the second fan, just the 1 fan with the additional heatsink area and heatpipes would be a big improvement and an easy job. (nothing other than back cover(s) and heatsink assmbly need be removed and reinstalled)
Even not messing w/ TDP limits, boost current/periods, etc. you can get better sustained performance simply by keeping it under the stock 75c throttle.
You may remove the 'dud' fan to reduce weight if you don't wish to do soldering and running of fine wires.
I was concerned of deckflex potentially shorting the heatpipes and GPU cooler baseplate to the bare solder joints, so I taped over the unused solderjoints with kapton tape. (Specifically used in electronics and transformer construction since it's insulative and non-flammable. This isn't probably necessary.)
As far as performance goes... (If you want to ask I dunno if he's on TPU, but he goes by pioneerisloud @ OCN)
I wish I had numbers saved, but going from stock single ch. RAM to dual ch. w/ TDP limits raised to 25W, we got near-to-over 100% performance increase across the board. Also managed to force the thing to pull over 100W according to AIDA64 under sustained load w/ the TDP limits @ 35+W and boost current + period maxed out. Nice and cool tho regardless; <85c w/o the fans ramping up beyond 'audible'. Goes to show how much the upgraded cooler helps.
At the more reasonable 25W cTDP boost It plays Crysis (lel, had to), and can play many modern titles with some pretties turned down and/or @ 1280x720/1366x768 (also upgraded screen to 1080p). The limited amount of RAM given to the GPU (1GB) is what's gimping it.
I've played Killing Floor 2 and Sonic All Stars Transformed Racing with him while he's been using it, and been impressed. I do not know what settings were set on KF2, since I know it can eat VRAM. Older games like source titles are very smooth. However, CS:GO does get a lil bogged down when a lot of smoke is on screen; but neither of us play CS:GO.
All in all, In some applications it was performing similarly (though generally slightly behind) to his i5 3570 + RX550 spare desktop, where not VRAM limited.
We were both VERY impressed with the outcome, and even the speediest laptops aren't built for the sustained boost (3.2+ allcore sustained) and (relative) cooling this thing has now. Even if they might be much more powerful (and expensive).
He's very pleased with it, and I'm slightly jelly. Was hoping to do something similar to a 4th Gen APU laptop once they come down in price, hopefully holidays 2020.
While I do think the project was financially justifiable, the biggest 'value add(ed)/(ing) feature' is the fact it 'was' a plain jane generic run of the mill low-mid consumer tier laptop, that's been totally rebuilt and modified to do something that few if any contemporaries could do. The Portal Vinyls totally add +5FPS too, right?