I've Replaced ~50% of My Custom Built Computer, and It Still Won't Stay Powered for More Than 10 Seconds

[Novvon]

I have a 2.5yr old custom built computer with the following specs:
Motherboard: Asus Sabertooth 990FX R2.0 ATX
CPU: AMD FX8350 Black Edition (8 Cores, 4.0 GHz, 16MB Cache)
Memory: Corsair DOminator Platinum 16GB (2 x 8GB) DDR3 - 1600
Video Card: Sapphire Radeon R9 280X 3GB Dual - X
Storage: Samsung 120GB SSD, Western Digital Red 1TB 3.5"
Power Supply: Thermaltake SMART SERIES 700W

About six months ago it started crashing upon waking it up (I religiously would put it to sleep once I was finished using it, unless it needed to shut down for an update, which I also did religiously). It wasn't a constant thing at first, I could still use it while I tried to google what was wrong with it and pull off every thing that couldn't be replaced.

Of the list above, the only things I haven't replaced is the video card and the ram. I've even replaced the case, because the thought was that maybe the case switch wasn't work properly since after I replaced the motherboard, CPU and power supply it wouldn't even attempt to power up after hitting the switch a couple of times (replacing the case now lets it attempt to boot up constantly).

Now the issue is that after 10 seconds, the whole computer just shuts itself down, its not even enough time to allow me to get the display to show the bios. When I first put it in the new case, the screen showed that the motherboard needed to be installed but before I could react to what the message was telling me on the screen, it shut off. The second attempt to boot I got into the BIOS, but again it shut down before I begin to understand the screen.

The suspicion is that its shutting itself down because it thinks something is wrong, but it won't give me any clue as to what. Even pulling out the RAM and the video card, I get no post-op beeps. With everything plugged in I get a Long and short beep, the motherboard flashes lights as it tests everything, and it seems like its business as usual until 6secs later is shut kills power.

I need to fix this thing, I've sunk money into it that I don't have because I need it for school. I also need to fix it because its bugging me to not know what is wrong with it. I took it to a shop when the issues first started, and they told me it was the motherboard. I'm now half way to just rebuilding a new sh** version, and its still not working...

 

[Viking2121]

You may have to reset the cmos/bios.

1) Start off by unplugging the PC from the wall, and holding the power button down on the case to drain all the power.

2) You will have to remove the video card so take that out.

3) You should now see the button cell battery, pop the battery out and wait for about 60 seconds before popping it back in.

4) Install the graphics card and the 6 or 8 pin power cabled to the card and plug the PC back in and see if it boots.

You may have to reconfigure you're boot order in bios. It sounds like the power supply to me, but you said you've replaced it and the motherboard. Have you plugged in the 8 Pin CPU power?

If all else fails, Leave the CPU in the motherboard with the fan plugged in, and leave only 1 stick of ram in, see if it boots, if not take the that stick out and try another stick. Unplug the HDD/SSD power cabled and data cables, Front USB and audio headers, any other Expansion cards unplug from the motherboard and extra case fans unplug, just trying to rule out each piece of hardware. Try another video card, I've seen this happen with a bad video card before.

Also if you are using a Liquid cooler, the pump could possibly have went bad, the system is turning off because the CPU is getting too hot, thats only if you are running a liquid cooler.