Monitor gets no signal from graphics card

[rynone]

Recently upgraded my system...bought a new motherboard, cpu, ram and hard drive. Plugged everything in, switched on the power and everything started to whir, but my monitor is getting no signal from the video card. I turned off the computer reseated the card, checked all the power connections and tried again - still nothing.

So I switched cards and did the whole thing again and I'm still not getting any signal. I've tried two different cards, two different cables and I know the monitor works because I had it plugged into my laptop.

Here's the specs:
XFX nForce 750i SLI Extreme Motherboard
Intel Pentium D 965 3.73 Ghz Extreme Edition Processor
4096MB PC6400 DDR2 800MHz Memory (2 x 2048MB)
1TB, 7200RPM, 32MB, SATA-300 Hard Drive
(First Card) EVGA GeForce 8600 GTS Video Card - 512MB GDDR3, PCI Express, SLI Ready
(Second Card) XFX GeForce 7950 GT Xtreme - 512MB GDDR3, SLI Ready, PCI Express

I upgraded my computer because I had an over heating problem and it fried my first card. The card was still under warranty so I sent it back to EVGA and now I have a "new" one. I haven't tried it in anything but this new computer yet and it's not working. Not sure if both cards are bad or if they aren't compatible or if I'm just stupid or something.

Help please!

 

[evongugg]

Welcome to the forums!

New build won't post checklist

http://www.tomshardware.com/forum/261145-31-build-post-checklist

 

[evongugg]

Did you plug in the 4-pin power connector?
Clear the bios.