Computer Turns on, No display.

I have a basic idea of what it is but I'd like a second opinion.
The error is quite simple, computer turns on but no display is shown. Two monitors give the same issue "No Signal".

Basically I purchased a open box motherboard (Biostar TA790GX 128m) from Newegg, much to my surprise the came in box with all accessories. The motherboard it self was inside the anti static bag with the foam under the circuit board. It really appeared new. I bought this motherboard for 3 main reasons:
5.1 Sound channel
2x PCI-E 16 Slots
ACC capability to attempt to unlock my AMD Phenom 550 x2

Basically I swapped out my old motherboard, a "Biostar A785GE" for the new TA790GX 128m and had the same issue with "No Display."
The LED Lights marked an error with the memory, so I immediately swapped out my current memory 1066mhz DDR2 Patriot PC2-8500 with Corsair 800 mhz PC2-6400. This did not solve the problem.
So I figure it was a motherboard problem, until I tried using 1x 1gb DDR2 800 mhz ram which then gave me LED lights for a "Normal Boot" but still gave me a "no display" problem.

I figured the motherboard wasnt good and swapped out the new motherboard for the old one. Much to my surprise I was receiving the same error as the new motherboar with no display with any combination of my ram (1 stick, or 2 sticks).

I tried the video card on my sisters computer and found it working, both the motherboards also have integrated graphics cards so I know it isnt a video card problem. I swapped the ram out, swapped the power supply. Tried no hard drives/ and hard drives.

At the end I tried doing a bare bones boot which is motherboard/cpu/ram/PSU which gave the same error. On the TA790GX 128m I managed to enter BIOS once using 1gb stick of DDr2 800 mhz but failed to enter again. it sometimes boots to the bios logo screen but freezes there.

My diagnosis is the CPU since it's the only component that has not be exchanged. 2 Motherboards, 2 memory kits, 2 power supplies, Different hard drives, 3 different graphical outputs (HD 4850, and 2 integrated GPUs).
The other thing is perhaps the new motherboard was DOA anyways since it first had issues with memory errors but then again this could be caused by faulty memory controllers in the AMD Phenom II 550 X2

I'd like to get a second opinion.

Summary of Tests done:
* Ram swap/combinations (1 stick 2 sticks, 800 mhz or 1066 mhz.
* Both motherboard had their CMOS cleared through jumpers
* Both motherboards were tried with basic components: CPU RAM PSU Motherboard
* Both motherboards beep continuously when no ram is present
* One motheboard TA790GX 128m recorded bad memory but goes away when 1 stick of DDR2 800 mhz is used. The other motherboard has no Hard ware failure LED lights.
* Old motherboard was working fine.
* 2 Power supplies where tried. Dynex 400w PSU (NEW from work), and NXZT 400w PSU. Both have been found working in past (Dynex was new). Both where tried under bare minimum test.
* CMOS Jumpers where placed correctly.

Possible Diagnosis:
2 Dead motherboards (1 previously working, the other not) very unlikely
CPU Failure: Likely
Two bad ram Modules: really really unlikely the 1066 mhz memory is new, bearly 2 days old.