Need Help Diagnosing an X79 System

[glossy flicker]

Nearing my wits’ end trying to get an old platform working. I’ve hit a point where one of three things is failing, and I’m not sure how to diagnose it more without buying an entirely separate machine to test against. I’ve got an Intel Core i7-3960x on an Asus Sabertooth X79 motherboard with 32GB of DDR3 1600 RAM. The system won’t POST and won’t output video (through a known-working GPU), and the motherboard is reporting that there is no RAM inserted (despite the fact that there definitely is).

I’ve tried cycling each RAM stick through each DIMM individually. I’ve tried reseating the CPU and the GPU. I’ve tried rebuilding the entire system and building it on a cardboard box to remove the possibility of shorts. I’ve tried flashing the BIOS using the quick flashback feature to no avail. I’ve replaced the CMOS battery. I’ve tried a known-good PSU, and so far, there is nothing that will make this system work.

At this point, I can see four potential points of failure:

1. CPU is dead.
2. MoBo is dead.
3. RAM is dead.
4. BIOS is Quite Dead.

I’m not sure how to proceed on this matter, or how to identify the failed hardware without an entire stable second X79 system available.

[hot valve]

Either the CPU is dead or the motherboard is failing. If the BIOs is identifying the CPU then it could be working. I would try putting the CPU in a different compatible motherboard or putting a compatible CPU in the "failing" motherboard. Either way, you will come to a solution.

[glossy flicker]

System isn’t even getting to BIOS. It won’t POST.

[hot valve]

hm

BIOS could've been corrupted in some way or motherboard failed for natural-various reasons.

[glossy flicker]

That’s the thing. I’ve gone over the motherboard with a fine-toothed comb. There are no swollen caps, and the leads and traces all look good—no corrosion to speak of. This has literally been sitting in a box in a closet in Phoenix, AZ, so no dust, no humidity, none of the environmental factors that might have caused a hardware failure.

The only thing I can think is that the CMOS got corrupted when I replaced the battery. Pulling the CMOS battery again should theoretically help with that, but it has not.

The difficulty I’m having here is that I’m not even getting a BIOS beep code. The only clue I have is that the motherboard has a number of diagnostic LEDs on it to help troubleshoot issues. When I power on the system, the light labeled DRAM_LED stays red, and through much Googling and Binging, I have discovered that this either means that: (1) I don’t have any RAM installed, or (2) the BIOS is corrupt.

The problem with the BIOS, though, is that ASUS went and switched file types for their BIOS ROMs, and at one point in the upgrade process, there was a warning attached to the download that said “you will not be able to go back from this point”

So I’m wondering if I bricked the MoBo—but trying to replace it is also proving to be tricky, because the CPU will only operate on the X79 platform, and that platform was remarkably short-lived (X99 came out almost immediately, and production on X79 stuff stopped at the same time).