I am seeking to help with an elderly neighbour's Optiplex 330 with E7200 CPU which is giving problems. Frequently won't boot with diag lights off-off-on-on. If it starts it mostly works fine but occasionally stops dead with lights off-off-on-on. Swapping out the ram from a working Inspiron makes no difference. The hard drive also tests good.

Diagnostics find nothing even though the diag lights suggest a memory fault.  Research on the web suggests that this is a common fault  with the motherboard in this model.

I was wondering if I can swap the motherboard for one salvaged from a Dell Optiplex 780 (part number 0C27VV). I know the ram is DDR3 as against the 330's DDR2. However I have some spare DDR3 modules. The original E7200 CPU seems to be OK for a 780 motherboard? The 305W power supply in the 780, which I no longer have, had the same rating as the 330? So I am left with the 40 pin front panel connector and cable. So far as I can see this is/was the same.

So will the 780 motherboard work in the 330 chassis?

All input appreciated.