|Have you tried troubleshooting any other hardware? I've seen these symptoms before and I have typically been able to fix it by replacing or removing the bad RAM.|
A quick way to test this is to take all of the RAM out except 1 stick and turn the comptuer on. If you get video on your screen, that stick is ok. turn it off and add another stick, if it works that one is ok too. If it doesn't thats the bad one. Continue this process until you have tested all of your RAM.
There are other things that could be wrong; for instance, it could be the RAM slot on the mobo. But for your needs, you either need to know if it works or it doesn't, not what part doesnt work.
If it still doesn't work after testing all of the RAM, there could be bigger issues (or ALL of your RAM is bad...), but the next step would be to disconnect all of the un-necessary hardware from your motherboard (i.e. dvd drive, any pci cards, secondary hdd, card readers, etc.) and try turning the computer on to see if it works. If it does turn on, it must be one of the hardware components. Troubleshoot them by adding them one at a time and try turning on the computer until you find the one that prevents the computer from turning on.