Which one is faulty CPU or Motherboard?


May 12, 2005
hi , this is following up form my previous thread, basically using the sticky thread on troubleshooting, iv narrowed the problem down to either the CPU or Motherboard.

The problem is that the pc wnt post, the fans run,lights come on, hdd light etc but nothing on display. at the moment its out the case on the motherboard box, with just cpu hs/f display. Iv tried with differnt memory, differnt PSU's differnt monitors, with / without a graphics card same outcome.

When there is no memory ram installed there are 3 beebs which suggest a memory issue, i put the memory in, silence.

Iv orderd some kingston ram using the configurator, which is due tomorrow so thats my last line of hope without returning components.

Is there anyway to tell 100% if its the Motherboard or CPU. If the cpu fan runs does it mean its ok? Iv Built 4-5 computers so i dnt think iv made a mistake in installing.

The Spec is:

Asus M3N78-EM
AMD Phenom II X4 955 BE 3.2 GHz
500w OCZ PSU
4gb oCZ ram ddr2


Jul 7, 2009
Hi, I had very similar problem today, it's posted on the forum too. The problem was very simple - I forgot to plug in 4pin power connector to mainboard... Hope it helps.