Hi, I just put together my first system with the following specs:
CAS: Antec Three Hundred
GFX: Radeon HD 4870
CPU: Phenom II X3 720
MOB: Gigabyte GA-MA770T-UD3P
MEM: Mushkin DDR3 PC3-1333 4GB
PSU: Corsair VX550W
DVD: WriteMaster SH-S223F
HD1: Samsung SpinPoint F1 Desktop Class HD502IJ 500 GB
HD2: Samsung SpinPoint F3 Desktop Class HD502HJ 500 GB
It started up fine, I set up the raid and started installing windows.
It did the BIOS look-a-like part, and was working on the windows installation when poof.
When I turn it on, fans move for about half a second, and then turn off.
I've tried taking out all components except for the mobo, cpu and psu, and it's the same result.
Sounds like you have a short. Extra standoff?
Try building outside the case with motherboard, cpu, beeper and power.
Listen for beeps and keep adding components.
Brand new system that works just fine for less than 30 minutes, then quits. Could be a bad PSU or mobo. But follow the checklist to be systematic about finding the problem.