GA-Z77-DS3H randomly fails to POST, error beeps, occasionally works - I'm fed up

[BlargTheDestroyer]

Back in April I bought a Gigabyte GA-Z77-DS3H motherboard with which to build a new system.  Parts other than the motherboard were:
-16 GB DDR3 RAM (G.Skill F3-10666CL9D-8GBRL, two 8 GB kits, which model is on this motherboard's Qualified Vendor List);
-Intel Core i5-3570K Ivy Bridge CPU;
-MSI Twin Frozr II OC GeForce 560 Ti video card (PCIe 2.0);
-Intel Series 520 120 GB SSD;
-Antec Neo Eco 520C (520W ATX power supply);
-NZXT Source 210 Elite case.

Resume from sleep didn't work from the start (apparently due to bad RAM, more on that below).  About three weeks in, the motherboard died completely, so I had to RMA it.

I got the motherboard back last Monday and, as suggested in the package insert, assemebled the system on a piece of cardboard, independent of the system case.  It worked fine, so I reinstalled everything in the case.  As of today, it is once again having severe malfunctions.

It turned out that two of my four RAM sticks were defective; they would prevent proper sleep/resume function in any PC they were installed in.  I learned that by installing them in an older PC that never had problems before.  So I RMA'd the bad RAM and am now using just the two remaining sticks (8 GB total).  So I think that solves the resume-from-sleep problems I was having before the RMA.

But even with the bad RAM eliminated, my GA-Z77-DS3H is still not working.  This morning, I tried to wake it from "sleep" mode.  It powered up briefly, not even long enough to display the POST screen, then shut off.  Then it powered up again on its own, emitted a long string of short, fast, error beeps, then shut down.  It will repeat this power on, error beeps, power off, cycle for as long as I allow.  Eventually, it will get to POST and load Windows 7.

Once again, I exchanged the original power supply (Antec 520C) with another power supply (Corsair CX 430, 430W).  I also removed the MSI video card so I could use built-in video, just in case the video card was somehow causing problems.  But the system is doing the same things.

I did manage to get the system working long enough to install the latest BIOS, version F6, but this has made no difference in the problems.

I am utterly fed up with this piece of garbage motherboard.  I suppose I might as well do another RMA, if Gigabyte will pay the shipping.  Otherwise I want either a completely new motherboard, or my purchase money refunded.  This whole experience has been extremely disappointing.  I built the system two months ago, but have been able to use it for perhaps 3 weeks total.  I have never had so many problems with a new system, or with one particular component.

[BlargTheDestroyer]

Found out something else today: on those rare occasions when the system boots into Windows 7, it doesn't keep working.  After a few minutes just sitting at the Windows desktop, the system will suddenly shut down completely.  Then it attempts to reboot, and we're back to the endless "powerup, error beeps, poweroff, repeat" cycle.

[Dark Mantis]

Hi

I think you need to go back to basics as it could be a short or something that is causing the problem.

The next thing is to remove the motherboard from the case and test it on the workbench.

Make sure that you observe anti-static precautions.

Lay some cardboard or use the motherboard box that is non-conductive on the worktop and remove the motherboard/CPU/heatsink/fan/buzzer/one stick of memory/graphics card and PSU from the case and put it on the cardboard. Add the keyboard and mouse and try and boot. The system should try and make a beep or series of beeps. Please post what sounds it makes.

[BlargTheDestroyer]

I tried the system-on-a-tabletop thing, both when the motherboard got back from RMA and just this morning.  I'm seeing the same behavior as when it was in the case.  Sometimes it appears to work briefly, then shuts down abrutply,followed by the error beeps and power cycling.  As before, on those rare occasions that Windows 7 actually gets to finish booting (often the motherboard will power down in the middle of the "Loading Windows..." screen), it will abruptly shut down within minutes or seconds of reaching the desktop.

I stripped the system down to the bare essentials, too - one stick of RAM, video card, mouse, keyboard, SSD.

This board is seriously messed up.

[Dark Mantis]

Try it without the SSD and GPU. See if it POSTs alright every time. If it does then instal the GPU and try again.