New computer has no video output

I purchased the parts below to build a computer.
After hooking everything up it seems to turn on and stay on but there is no video output.
I have swapped to a different video card with the same result.

I confirmed that I have the 12 pin connector and both 4 pin connectors on the motherboard and on the video card I made sure the power connectors were listed there. The second video card I tried did not require extra power connectors.

I have the ram in channels A1 and A2, leaving B1 and B2 empty.
There is a single power indicator on the motherboard and when connected to power it lights green.

There are no system beeps or anything when it starts up but it doesn't seem to power down or reboot or anything. I took one stick of ram out of A2 and now it gives 3 long beeps when starting up but still no video output.

Intel DP45SG Motherboard - Intel P45 Express, Socket 775, DDR3 1333/1066/800 MHz, 7.1 Audio, CrossFire (2) PCI Express 2.0 x16, SATA RAID, eSATA, USB 2.0, Firewire, S/PDIF, Gigabit LAN

XION Power Real 1000W ATX Power Supply

Two Crucial 2GB PC3-8500 1066MHz DDR3 SODIMM Laptop Memory Upgrade - Non-ECC

XFX HD487AZWFC Radeon HD 4870 Video Card - 1024MB GDDR5, PCI Express 2.0 x16, CrossFireX Ready, (Dual Link) Dual DVI, HDTV

HP HPDVD1270I Multiformat DVD Writer - DVD+R 24X, DVD-R 24X, DVD+RW 8X, DVD-RW 6X, DVD-RAM 12X, SATA, Lightscribe

Intel Core 2 Quad Q9505 Processor BX80580Q9505 - 2.83GHz, 6MB Cache, 1333MHz FSB, Yorkfield, Quad-Core, Retail, Socket 775, Processor with Fan

Four Hitachi OS00163 Deskstar IDK/7K Internal Hard Drive - 1TB, 7200RPM, 32MB, SATA-3G
 
Sorry I forgot my original order I got the wrong memory

Actually Crucial 2048MB PC8500 DDR3 1066MHz but I'll check that post

1. Switch the monitor to a second output port if present on the graphics card and see if display is restored. If it is, the other port must be the problem.
---First card has 2 DVI ports and I tried both
---Second had 1 DVI, 1 HDMI, 1 VGA and tried all three as well

2. If (1) fails, plug the monitor to the motherboard's VGA adapter and check. If it works, then your monitor is Ok. Graphics card might be the problem.
---Unfortunately my motherboard does not have an on-board VGA port

3. If you have determined that the card might be a problem, try out a different card. If it works the issue is resolved. If not, it may be the graphics card slot on the motherboard (PCI / PCI-E/ AGP).
---As mentioned above I have tried two video cards
---Motherboard has 2 slots for the video card and I have tried both

4. If (2) above fails, then the issues could be varied. PSU problem / motherboard problem / RAM / the monitor itself. It must also be determined if the mobo is failing the POST. After this stage, to me, it's difficult to determine what to do. If a new monitor can be arranged and if it works, then its fine again as the problem is determined.
---Monitor works on another computer
---Also tried a second monitor and still no output
 
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