My new system will not post. please help.

posted over at anandtech but no response yet.
okay. so i was going for a budget gaming pc and i had bought everything i needed:

AMD Athlon64 X2 5000+ Black Edition
Thermaltake SopranoRS Case
Antec Earthwatts 430W PSU
Wintec AMPO 2x1gb ddr2 800
150gb Seagate Caviar HDD
Phillips DVD burner
XFX Geforce 8800 GS XXX alpha dog yada yada yada
GIGABYTE GA-MA78GM-S2H Mobo
CoolerMaster Hyper TX2

i put everything together and connected all the power cords and turned it on.
everything spun up correctly but the monitor would show nothing.
the little yellow light never turned green.
i'm using an old Dell CRT from the previous pc that we had.
the HDD worked, i could hear it spin up.
the DVD bay worked, i could open it up.
the cpu cooler, system fan, and video cards all worked because i could hear or see their fans.
but the system wouldn't post.
the thing is, this case didn't come with a case speaker and the old dell that we had used a series of lights on the I/O panel to indicate problems so i don't have any idea as to what the problem could be.
gigabyte said that i should RMA both the processor and the Mobo because i had no way to isolate which of the two it could be.
so i did.
and i waited two weeks for the new hardware to come in. after installing it yesterday, the same thing happened. the same exact thing.
i'm going to take it to the shop tomorrow and see if i just made a bonehead move while installing everything but i figured since they're closed today that i could post here and maybe find some sort of solution so i wouldn't have to worry about going to town.
please, if anybody has any sort of advice or solutions, do not hesitate to lay them on me.
.
.
.
the motherboard has an onboard speaker apparently because if i put in the gfx card w/o the 6-pin cord plugged in, it gives me the long beep to tell me that the card isn't installed correctly.
i unplugged the dvd drive and the hdd and have tested both sticks in all 4 slots but still nothing as far as the display goes.
if i plug the 6-pin back in then i get no beeps which is supposed to mean that there is some kind of board, cpu, or psu problem, right?
is it possible for only one of the 12v rails to go bad?
because everything else gets powered up.
i will try to make sure that the cpu is lined up correctly but i really hope gigabyte didn't send me another board DOA...
.
.
.
cpu is lined up right.
i'm out of ideas.
i've tried putting either stick in each slot one at a time and tried booting to no avail.
i've tried hooking up monitor to mobo and gfx card.
i've tried using the dvi to vga adapter for all dvi ports.
i've tried using all vga ports.
i've tried unplugging everything and booting.
i don't know what to do.

hah. yeah.

I recently saw a faulty cable being the issue with a no-POST on this forum, so definitely try to check the cable. Also, that 4-pin ATX power often messes me up when I first build. I never remember it.

Also, try a single stick of RAM at a time. (And switch out if one doesn't work).

-Check VGA cable
-Check monitor brightness (don't laugh, it happens)
-Check CMOS Jumper

That's what I can think of now, might try a different monitor/cable, if possible.

If your broke the system down to CPU, 1 DIMM RAM and video card and get nothing, you know it's one of those elements or the MB. You would have to have spare parts and start swapping out video card, CPU, etc.

Try this. Be sure the system has a working speaker connected to the MB speaker header to allow audible BIOS beeps. Take out ALL the RAM. Boot the system with no RAM. If you do not hear the MB beep signifying there is no RAM in the system, you likely have a bad MB. The CPU is suspect also.