What does he use the 7600x for? If it's just for gaming reasons then he might want to first try setting it to 65w eco mode in the BIOS. You're not gonna lose any gaming performance and it'll set the power limit to 88w (because 65w eco mode means 88w...for some reason) which absolutely shouldn't cause any VRM overheating on that board.
Moreover, I'd be curious as to how he figured out it was the VRMs overheating versus something else. The S2H's VRMs aren't too bad so it surprises me that he would be getting throttled like that unless he was really pushing that 7600x to its limits in an all-core workload or something.
I'd like to know what your definition of "aren't too bad" is. It's Gigabyte's favourite unheatsinked 4C06N setup with only 5 undoubled phases. That's comparable or worse current handling than 3 doubled lo-side found on absolute bottom of the barrel AM4 boards. It literally doesn't get any worse.
Since like 5 years ago it's common knowledge that even 65W (88W PPT) CPUs are a struggle for doubled 3-phase Vcore. 7600X is a 105W (142W) CPU.
My friend has been having a lot of issues with his MB VRMs overheating!
The motherboard that he picked was the cheapest AM5 one on PCPartPicker:
Gigabyte A620M S2H Micro ATX AM5 Motherboard
The cpu that he bundled it with is Ryzen 5 7600X.
I suggested him to add some heatsinks to aid in cooling however I talked him out of using heatsink plaster as that stuff doesn't conduct heat that well and is pretty permanent! So are there any good thermal pads that are self adhesive or semi adhesive [either that or zipties :V]?
I don't know much about thermal pads because I haven't really used them that much.
First step is to get a spare small diameter fan (e.g. 80mm) and either lay it on the VRM directly or stand it up on the back of the GPU pointing at the VRM and just blast it with airflow. Also you've not said anything about the rest of the system, improving system airflow (especially rear and top exhaust in a conventional layout) also helps.
If it's still a problem, you can look for those tiny stick-on heatsinks for individual mosfets like this, and combine it with said airflow:
And find Eco Mode in BIOS to drop it down to 65W TDP (either 76W or 88W PPT, not sure which it will be for S2H). It's a 6-core, no reason to be running that much power day-to-day, especially given how aggressive Zen 4 is with any extra power headroom. 7600X is one of those SKUs that should not exist; turning it into a 7600 through Eco Mode will be easier to handle all around.
it's a bad board after all.