The Xclamp is Microsoft’s weird heatsink retention mechanism that puts undue stress on the Xbox’s motherboard, leading to warpage and then finally the solder under the GPU/CPU gives way and then you get an RROD. I’m replacing that with a couple of screws and washers to prevent board warp.
1st you’d need to enlarge the stock screw holes on the chassis to 5mm dia to get the new screws to fit.
Then you’d need to get hardware to mount the whole thing on. You’re gonna need a couple of M5x0.8x16mm screws and 1mm thick washers to get the dimensions right.
After getting all the hardware, take off the stock retention studs on the bottom of the heatsinks, and also cut away and flatten the stock Xclamps.
Once done, start putting in the hardware.
I use some tape to temporary prevent the screws from falling out when I tip the chassis over.
The flattenned Xclamps go on, and then enough washers to make up 3mm height.
A piece of 4mm foam underneath provides support around the CPU and GPU area.
Put in the heatsinks and lay the Xbox on it’s side, then tighten the fasterners, in a cross pattern to exert even pressure.
Once done, put together the Xbox as per normal.
Credits to http://xbox-experts.com/tutorial/team-hybrids-ultimate-xclamp-fix-released/ for giving me this idea in the 1st place.