HP Workstation Boot up Problem

[KGreave0]

Hello, I have a problem that I have been trying to fix for a while. I bought a refurbished Workstation. The workstation is an HP/Compaq Pro 6200.  Whenever I start the computer the fans spin up to the max. No input is displayed on the monitor.  The HDD LED does not turn on. After exactly a minute the fans spin down to normal, The HDD LED is lit, and input is displayed in the monitor. I tried switching out the RAM for new RAM. It did not work. I'm wondering if it could be the motherboard or the PSU. If it was the motherboard shouldn't there be more problems arising than just powering on? Everything works after it powers on normally. The only other problem is the two bottom front USB ports do not function at all. The top two work. I'm thinking it is a faulty USB hub. Now If the two bottom ports do not work shouldn't the other two not work as well? If someone could help me out that would be great.

Thanks

[Lil_Boy_Blue]

Hi

I would not rule out the CPU.