[Solved] Breadboarding new build, w/o memory = beep, w/memory = no POST

I'm breadboarding a new system. PS (both 4 and 24pin), CPU, and power button/led/speaker connected to mobo with no memory results in mobo led coming on and a series of beeps (for no memory), but when I add memory there is no single POST beep, no video from onboard video (mobo led still on).

My question is about diagnostics - If I get the 'no memory' audio warning, but then get nothing with memory inserted, what can I rule out as working and what might need replacing? Help please!

And yes, i've read http://www.tomshardware.com/forum/ [...] -problems. I have two sticks of memory and four DIMMs, and i've tried each stick in each slot (8 iterations) plus both in the paired slots (two more iterations). Nothing. I've also tried both onboard DVI and VGA video outs, but with no post i'm not expecting this obviously.

Basically brand new setup - all the components are straight off the mobo 'suggested hardware' list, so i'm pretty sure compatibility isn't an issue. but at this point, who knows.

Build:
Mobo: ASUS M4A78-EM (microATX)
CPU: AMD Phenom II x4 995
Memory: G.SKILL 4GB (2 x 2GB) 240-Pin SDRAM DDR2 800 (PC2 6400)
PSU: X-Power 585

I reset the CMOS, and the same lack-of result. I would guess (and it is a guess) that since the mobo has never been used before, it has whatever factory settings for memory already in place, and resetting the CMOS would only return these to the already-in-place settings. It was worth a "just for the heck of it" though.

I guess my larger question is that I have a week and a half while I can return the motherboard and the processor. What are the chances that this weird behavior is caused by one of these? I'm not quite sure exactly what the processor's role is in the POST process. The motherboard seems to power on and detect a lack of memory, so my best guess at the moment is that the PSU and the motherboard are okay... although I'm quickly reaching the edge of my build diagnostical skills. ANYBODY? Experienced help is greatly appreciated!

Yup - I have both the 4 pin power plugged into the motherboard, and the 20+4 pin power plugged into the mother board. The motherboard LED comes on when I plug in the machine, and the cpu fan starts up when I hit the power button.
I know the mobo led and the cpu fan are probably associated with the 4pin power - is the 20+4 pin power connection required to POST? If so, maybe this power connection is faulty. If only the 4 pin power is required to POST, then I'm back to square (n)one - because it seems to be working.

Can you verify what CPU you have??? You state that it is a Phenom II x4 995... is it really a 995 and not a 955???

Even if it is a 955, the 955 isn't supported till BIOS ver 0504 and your board might have an older BIOS on it.

This is what ASUS says about the ver 0504 BIOS: *Updating the BIOS with the latest BIOS version will enable the motherboard to support AMD AM3 945/955 CPU.

Granted, a motherboard with a BIOS that doesn't support a specific CPU MAY still boot up, but it may also PREVENT it from booting up. I had that issue with a laptop, with it's original BIOS it would only boot a CPU up to 700MHz (an old pentium 3 system). But with the newest BIOS it would boot a 1000Mhz CPU.

So, the ver 0504 BIOS or better supports the 945/955 CPU's and the 995 CPU doesn't seem to be supported at all.

If it is a BIOS issue, you can:
1. RMA the board and hope the new board has the needed BIOS installed.
2. Procure a different CPU other than a 945/955 so it will boot and allow you to flash the BIOS to the latest ver (0907).

If you do have a 995 Phenom II, your gonna need a different board.

Just my thoughts so far.

Ok.... I lied.... one more thing.

To test with a cheap CPU... you could get a Sempron LE-1250 from newegg for $30, free ship.

So I just got off the phone with ASUS (very helpful and nice!) and there is, on the motherboard, a sticker with a TON of little numbers on it... and the last four happen to be the installed bios version! That's good news.

Bad news - it's 0312, so not high enough to support my fancy new processor. More good news, I guess, is that the bios chip is removable (some aren't), and since the board is under warranty, they're going to send me a chip with the latest bios that I can throw in there (just pay shipping and handling!). So, a little more money and hullabaloo, but still better than RMAing the mobo/processor, or buying a $30 processor just to flash the bios.

thedraac - thanks soooooo much for your insightful comments. The only way to learn this stuff is the hard way, but it's always nice to have somebody more learned there to lend a hand. Thanks!