I've just bought a brand new computer. second time putting one together myself.
Asus M5A99X EVO
1000W ATX PSU
Sapphire HD Radeon 7870
AMD FX8120 3.1ghz
Corsair hydro H100
CM Strom trooper
I'm getting a red-light on my mobo as well, tried pulling it apart several times and attempted the breadboard as well. but didn't get any sound-notification from the speaker that came with the case. Also I get no reaction on booting visually, fans run normally, as well as the graphics-card's fans. They also slow down after the initial startup. but no bios-screen no nothing.
I'm thinking you probably need a BIOS version update because it's not recognizing that particular CPU. Get ahold of a Phenom II cpu and see if it boots up. If it does update bios to the current version from asus website. Then reinstall the FX-8120 CPU.
BTW why do you need a 1000W PSU. That system could run fine on a 500W.
The BIOS supports the CPU, so the issue is not there. I would test the board outside the case, having only the CPU and CPU fan installed. You should get the error beeps signaling that no RAMs are installed.
All fans are spinning, including the cpu fan, as well as the GPU-fans
The speaker doesn't work on the current board, it is connected according to the manual. and my old board had one built-in, so don't have a way of testing it.
As for the motherboard. I don't know, would I send it to ASUS for a new one, or the retailer of which I bought it.
WOHO! Success! to a certain degree anyway. Turns out I had fastened the screws for the cooler-mount too hard. can get into bios just fine now.
Now I bumped into another issue. I get to the windows 7 startup-screen, I've got 2 drives with 32-bit on one of them, and 64 on the other.
On both instances, once it loads for 2-4 seconds, the screen loses signal, and reboots.
In the end you can slipstream the SATA driver and the SP3 using nLite and install the XP.
Try starting Windows in Safe mode (use F8 for bringing the menu - http://www.youtube.com/watch?v=x2o18BRBhvo). See if it does work.