new computer won't POST

[Doc_Dallas]

My mainboard crapped out while I was backing up everything to an external HDD, so I replaced it. My old power supply was 20W too small, bought a new one120W larger for this m-board (an extra 100W over min). No post. No logo nothing! Had to buy new memory & boxed CPU. New HDD, too. I've tried swapping out the m-board, , the CPU, then left out memory and the only thing the computer does is spin the case fan. I'm using the onboard video instead of the PEI vid-card and I have nothing else attached, I have tried with & without a HDD, memory and CPU and nothing at all happens! All the normal things that I've done over the past 12 yrs hasn't worked.

 

[g-unit1111]

Knowing the make / model of the following components: motherboard, CPU, RAM, PSU, HDD, GPU would help to diagnose the problem.

 

[Doc_Dallas]

Gigabyte 880GA-UD3H, Athlon II tri-core boxed CPU, Patroit 4GH Dual channel DDR3 10333, Diablotech 600W ATX, 250 GB WD HDD