Some people who have experienced this fault might find this of some use. (From gigabyte tech support)
Dear Sir
Please kindly do as follows:
- remove power cord from PSU
Done
- remove the M/B from the case
Done
- only install the basic components on the motherboard
Done
–CPU, CPU cooling fan, one memory module, VGA card (if MB hasn't onboard one) and power supply.
Done
- make sure that 4/8pin 12v connector and MB 20/24 pin connectors from the PSU are both plugged to the MB.
Done
- remove CMOS battery - clear cmos by short circuit of "CMOS CLEAR" pins or pressing "CLEAR CMOS" button (if available)
Done
- wait 10 minutes - install CMOS battery & connect the power cord to PSU
Done
- try to start the MB, it may restart a few times, please be patient
Done
- when finally MB has started then upgrade the latest bios version from our website using Q-Flash utility
Done
- then install second RAM stick
Done
You can find current BIOS version based on the following info:
http://ggts.gigabyte.com.tw/eService/motherboard_bios_ver.htm
Please upgrade to the latest bios found at:
http://uk.gigabyte.com/support-downloads/download-center.aspx (type your model name in Option 2. Search by Keywords) using Q-Flash utility embedded inside our bios setup. To enter Q-Flash press <End> key during the POST or <F8> key in BIOS Setup. The guide is available at:
http://uk.gigabyte.com/webpage/20/HowToReflashBIOS.html Worth to see this topic also:
http://forum.giga-byte.co.uk/index.php/topic,2441.0.html
You can try to change the PSU for different vendor /model just for checking.
If all of above fails then contact the place of purchase for checking your product and arranging RMA if necessary
Regards GIGABYTE UK Support
I have tried all the above apart from a different psu.