At first glance, this looks like a simple problem:
Computer won’t start. I re-seat the RAM, and it starts correctly.
I close the computer case, and when I start the PC again, I hear a familiar beeping sound (no RAM).
Since there isn’t much dust inside the PC, I re-seat the ram again, and I can eventually get the PC to start long enough to run a RAM test… but I find no fault… and the PC is now working fine, and I can’t re-generate the fault.
I ask the customer to keep an eye on it, and to call me if it happens again.
Well, I get called again just 1 month later… with exactly the same problem.
So all I can figure is that the RAM has an intermittent fault, so I replace the RAM.
Oddly enough, that seemed to fix the problem.