I am having the same issue as the other posts. I am building a brand new systems and when i turn it on, everything seems to work (lights on, fans spinning, except nothing is showing on the monitor (no signal)and keyboard and mouse not working either. My specs are: Apevia X Cruiser Mid tower ATX Intel DX58SO ATX LGA 1366 mobo OCZ Gold XTC 6GB DDR3 Memory kit (3 2gb Memory modules) Intel Core i7 920 cpu XFX GS250 GeForce GTS 250 512MB DDR3 PCI-E 2.0 Video card 2 Samsung SATA DVD/CD drives Western Digital Caviar 640 GB Harddrive 32mb cache, 7200RPM SATAII Corsair 750W PSU Note: I use a third party heat sink and 120mm fan that's compatible with the i7 920 CPU since I broke one of the legs of the stock heatsink when i tried to push it down onto the mobo.
I'm sure you've already seen the READ before posting about boot problems! sticky. You need to perform EVERY step in the checklist to properly troubleshoot your problem. Most people coming here for help with your problem say they've read the checklist. Most of the time the resolution to their problem was right there in the checklist the whole time. For some reason a lot of people seem to think some of the suggestions don't apply to them.
#2 on the checklist is by far the most common mistake. RAM problems and shorts are also fairly common. That's why the suggestions to try each stick of RAM by itself and building the system outside the case to rule out a short are there. The checklist contains troubleshooting ideas from many forum members and is regularly updated.