Won't boot up with battery

[izerogue]

I assembled my computer about 4 years ago. It had been working fine until recently, it couldn't be switched on any more after a normal power-off. The PSU fan didn't start when pressing on the power button at all. All the LEDs on the MOBO looked normal.

I stripped off the graphic card, RAM, all the cables (HDD/keyboard etc.), and found it only booted up with a single RAM (I have 2 x 4GB), without the BIOS battery. As soon as I put anything else on top of this build, or put the battery back in, the problem came back. I tried to replace the battery but to no avail.

I had to keep the computer switched on and hot-plugged in the video card, the other RAM in DIMM2, and all the cables. I know this is very dangerous but I had no choice. Fortunately the computer works fine right now, even though I don't think it can be turned off anymore - unless I wanna go through the unplugging/hot-plugging steps again. I haven't put the BIOS battery back in either.

The spec:
PSU = EVGA 750W GQ (I replaced it today, the old one Antec 650W should still work)
MOBO = Gigabyte GA-Z68X-UD5-B3,
CPU = i7 2600K
RAM = Cosair 2x 4GB DDR3 1600Hz
Graphic card = GTX980

Can anyone please shed some lights on this problem? It feels like a BIOS issue but is it possible to fix it?

Many thanks!

 

[cin19]

Using the onboard iGPU from the i7, whatever you do just boot the PC. After that check the MB BIOS to see it is the newer version F10 or not, yes it isn't. Then update it. http://www.gigabyte.com/products/product-page.aspx?pid=3848#bios Also may update the chipset driver too. https://downloadcenter.intel.com/download/20775/Intel-Chipset-Device-Software-INF-Update-Utility-?product=1145
Note after update the BIOS, you need 1) make sure the HDD with OS is connected into the 1st SATA port. 2) make sure the HDD is the 1st boot order, or the DVD/CD=1st, HDD=2nd. 3) make sure to set the RAM in XMP profile.

After that try boot the PC with or without the CMOS battery to see you still have the same problem or not. If you still have the same problem, try http://www.tomshardware.com/faq/id-1753671/bench-troubleshooting.html