Here's some specs I took from 9800, seems the same as the previous 9700. (was mainly info to mill shim avoidance into my block base)
Mounting holes are just a tad smaller than M3 so an M3 screw / bolt would be a tight fit or cut a thread slightly if forced in the hole. On the mounting pressure you'll be limited by card bend if you just use bolts through the holes, (so don't over tighten). To get a decent mounting pressure you need a retainer that presses on the back of the PCB opposite the core. I made one that has a raised centre and used a mica shim to prevent PCB contact / damage. The "copper retainer bar" was bent in a slight "V", so becomes straight, (level), when tightened giving a spring retention effect. This is just an educated guess as to mounting pressure, but is far more than standard push pins give, not that it is of huge importance with VPU heat levels, as long as it is secure enough, it should be fine.
