Just recently bought a new CPU (which is 100% supported by my Motherboard) but been having the issue of when I replaced it the machine would power up (fans spinning, hard-drive going etc..) but no VGA output onto my monitor, even when waiting for a few minutes nothing and as soon as I put my old CPU back in bash 5 seconds and I am getting a VGA output onto my monitor.
I am wondering what you think the cause of this may be?
I have taken it back to the shop now twice and complained but he has just said "Tested it, worked fine" but wouldn't allow me to see it being tested (gets me suspicious really) & also I have tested this in 2 machines with the same result.
Shop I bought it from tested my system & the shop I went to for a second opinion only tested the CPU. If it isn't a CPU fault why does the computer work fine as soon as I replace it with my old AM2 processor (Yes, my motherboard does 100% support this current processor).
If the X2 250 works fine in another computer I am really not sure what the problem could be. Try swapping the memory as sometimes memory can be a bit finicky at times.
You could also to reflashing the bios to a slightly older version and see what happens as sometimes the latest bios updates are betas.