Intermittent POST Problem

[gearomatic]

I have a problem with my computer Failing to post about 98% of the time. Lot of info here, sorry for it being a bit unorganized. I've been up all night working on this

Once it POSTs it is fine, but it hardly ever POSTs. When it does start, doing a Restart through the OS works fine, it Posts (takes about 20 seconds to do so, but it does) and reboots like normal.

When it fails to POST, it does nothing but spin the fans (external fan controller). It flashes something quick and incomplete on the error codes, but it is so quick that I don't think it even lights up 1 of the 2 numbers. Looks like it could be a 6, and it flashes super quick when I hit the power button and when I kill the power.

My mobo has the Dual Bios which does Jack in my case. Bothe the back up and the Main Bios do the same thing.

Switching the Second switch (Dual Bios or Single Bios option) changes it a little. In Single Bios it does as stated above, Spins the fans and does nothing more. In Dual Bios the fans spin for about 5 seconds, then they stop for about 2 (sounds like a system shut down as the power supply makes a click like the computer was turned off) then it starts up the fans and stops again. Over and over.

When it does POST I usually have to sit there for 5-15 min, turning on the computer, Killing it on the PSU, and turning it back on. my only indication that I WILL POST is that it will start to spit out Error Codes for ~10-20 seconds before POSTing. If i can get it to POST i will try to take a video so I can write down as many as I can.

Specs: CPU: Intel Core i7-4790K 4.0GHz Quad-Core Processor
Motherboard:Gigabyte GA-Z87X-UD5 TH ATX LGA1150 Motherboard(Manual: download.gigabyte.us/FileList/Manual/mb_manual_ga-z87x-ud5-th_e.pdf)
Memory: Crucial Ballistix Tactical 32GB (4 x 8GB) DDR3-1600 Memory
Video Card: Gigabyte GeForce GTX 770 4GB WINDFORCE Video Card
Video Card: Gigabyte GeForce GTX 770 4GB WINDFORCE Video Card
I am NOT running SLI
Power Supply: Corsair 1200W 80+ Platinum Certified Fully-Modular ATX Power Supply
Operating System: Microsoft Windows 7 Ultimate SP1 OEM (64-bit)

Steps taken so far (in more or less the order I tried):
Reseated all RAM
Cleared Bios
Reflashed the Bios (using @bios)
Tried 1 stick of RAM
Cleared Bios
Tried 2 Sticks of RAM
Cleared Bios
Removed 1 video card
Cleared Bios
Removed the 2nd video card
Cleared Bios
Removed the PCI USB 3.0 card
Cleared Bios
Removed all HDDs/SSDs
Removed all the USB adapters at the headers
Removed all the front panel/audio at the headers
Reseated the CPU and added new paste
Cleared Bios
Drew a pentagram on all Components and read Twilight Backwards
Cleared Bios
Tried an alternate PSU

I really want to avoid purchasing a New Mobo (not sure if I would go with Gigabyte again, they were a real pain when my fans stopped reporting there speeds to the OS/BIOS and "fixed it" [hint, it still doesn't work])

And I don't want to shell out the dough for another copy of W7 since its tied to the motherboard now.

I would really rather Put the time and effort into fixing it if possible.

My current course of action is to get it to POST and to flash the Bios with Q-Flash to see if that helps, then try to see if Gigabyte will replace the board...

ANY help/suggestions are welcome, Thanks in advance!

 

[thx1138v2]

The only thing that jumps out at me is the "external fan controller". It could be that the fan controller isn't communicating properly with the mobo and the mobo thinks the fans are off so shuts down. You said that they "fixed it" but that may still be the problem if it isn't reporting properly. Since that was an earlier problem I wouldn't count on it being fixed. You might try removing one or both graphics cards to keep the heat down and connect the fans directly to the mobo just to see if it POSTs.

You won't have to buy another copy of Win7 if you replace the mobo. You can call microsoft and explain that you had to replace the mobo and they'll activate the same copy again. The same applies to replacing a hard drive.

 

[gearomatic]

The only thing that jumps out at me is the "external fan controller". It could be that the fan controller isn't communicating properly with the mobo and the mobo thinks the fans are off so shuts down.

Sorry, should have been more clear. The Main CPU fan is going into the Main CPU header on the Mobo. All my other fans are going to the fan controller which is independent and does not talk to the Mobo.

The problem Still Exists when I have a Fan Plugged into the Main CPU fan header.
Also, shouldn't it give me a Fan Failure Error instead of nothing?
It also does not account for the machine Working properly every once in a while.

Good thought, but I was unclear with my wording. thanks though! I appreciate it.

When the system does boot, the hardware monitors in both the BIOS and the ones I have on windows all happily report 0 RPM on every fan, regardless of weather they have a fan plugged in. When Gigabyte failed to fix this, I got that independent fan controller as a bit of insurance for myself.

 

[thx1138v2]

When the system does boot, the hardware monitors in both the BIOS and the ones I have on windows all happily report 0 RPM on every fan, regardless of weather they have a fan plugged in.

If the BIOS is reporting 0 RPM but it still boots occasionally I guess that's not the problem.

It sounds like something on the mobo is borked since you tried both BIOSs. I would disassemble it and look for contact between the bottom of the mobo around where the fan connector is and the case. The other thing to check is that you've got all of the mounting holes in the mobo populated with screws to metal standoffs to the case and that they are tight and making good contact to make sure it is getting good grounding.

If it's not either of those I'd either RMA the mobo or try another brand. Gigabyte usually makes good mobos but every manufacturer puts out lemons occasionally. Personally, I like Asus.

 

[gearomatic]

CPU was dead...