No beep, fans running, DVD drive working, no signal on monitor

[sexymonkeys]

I have built my first ever PC, but I just can't get it working.

I am pretty sure I've built it correctly, but the only things working atm are the fans + gpu fan and the DVD drive. Not sure about the HDD because I have no way of checking. My hardware is as follows:

PSU: Corsair VX550
CPU: AMD Phenom II 955
GPU: XFX Radeon HD 4890
MOBO: Gigabyte GA-MA790X-UD4P
RAM: G-Skill 4GB DDR2-1066
HDD: Western Digital Caviar GP 500GB
DVD: Samsung SH-S223F
CASE: Cooler Master Storm Scout

When I turn my PC on as I said, there is no beep, no signal on monitor, but the fans are running and the DVD drive works. When I turn it on, I am unable to turn it back off without using the power supply switch (which I'm afraid might damage my parts, but I have no way of checking if I'm fixing the problem with changes without doing that). Does anyone have any idea why this might happen?

I think I might have a faulty motherboard, because when I had it delivered I noticed there were two scratches on the bottom of the board that were very noticeable. I'm afraid this might be the problem, but I'm not quite sure. Are there any suggestions on how to fix this?

 

[shortstuff_mt]

The checklist in this sticky was created to help troubleshoot problems exactly like yours.

READ before posting about boot problems!

I would perform every step in the checklist. #2 on the checklist is the most common mistake.

 

[sexymonkeys]

Wow thank you. Didn't realize about number 2. Did that and it booted properly straight away, though I'm still getting no signal on my monitor. Hopefully I can fix that by doing all the steps now.

 

[fressko]

I cannot overstate the usefulness of this diagnostic thread:

http://www.tomshardware.co.uk/forum/261145-31-perform-steps-posting-post-boot-video-problems

Please read at the above link, it will 99% solve your problem!!!
For me it was step 6 because of a faulty ram stick