Weird GA-EP43-UD3L Issues

I bought and built a new computer parts with the following configurations-

Crucial 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1066
BFG Tech BFGEGTX260896OCE GeForce GTX 260
Intel Core 2 Quad Q8300 Yorkfield 2.5GHz
Antec Basiq BP500U 500W PSU
and Gigabye GA-EP43-UD3L

The computer is working great for the past few months but these days when I came up to my machine then find that it continually restarting. Now when I switched it on, it will post and sometimes boot up the windows. After less than 5 minutes it will automatically restart and continually booting without posting. (the fans will stop, the "phase leds" will turn off, then everything turns back on and the process again applied ). I have played with unplugging memory and replugging it. I have clean the dusts on the system. I have also reset the BIOS and pulled out the CPU and videocard just to see if reinserting hardware would resolve it.

Hello dude,

You have to change something that can make effect on the hardware and software level. Have you used each stick of RAM particularly in any of the slots? If it is not like that then I would try out each stick particularly.

/edit

This is kinda out there, but maybe try a another video card (one that doesn't need as many amps on the 12v rail). That PSU may not be adequate enough for your GTX 260. I am not sure that how many amps are needed on a 12v rail for a GTX 260, but you might investigate into that.

It's sure that your psu is failing or that there is a loose 24-pin or 4-pin ATX_12v connector. There are so much things on this in a bit. Your symptoms are same as to a setup with wrong BIOS configurations. You need to use this BIOS template to post your recent settings.

After the posting of your recent BIOS configurations :
1) Load optimized BIOS settings from Entry BIOS screen.
2) Just follow the suggested BIOS settings in the starting of the post and find out if your system will boot with only one memory module in slot #1.
3) With your 2x2GB of Crucial 1066 DDR3 memory, MCH Core = 1.20 - 1.24 should perform OK.
4) Just keep your new BIOS settings as a stored BIOS profile (F11 from the main bios screen) and provide it a meaningful name.
5) Save settings and quit form there.
6) Boot within windows using only one memory module and find if your system is stable. If it is not like that then explain in detail what issue is getting generating.

Your psu contains two 12 volt rails, with every rail rated at 18 amps each, and the video power cables are both plugged to the same rail. If your psu is working properly, this is powerful enough for common use of computer, but probably not powerful enough for executing demanding games or programs. Currently, I am
getting that you do not have your computer overclocked.

RoscoP's advice are better. If the modified BIOS configurations do not support to do this and I suggest that you beg, steal a somewhat maximum powered psu (at least 600 watts) and check your system with the borrowed psu. You might require to borrow a set of same memory to test with. Did you ever do any extended stability testing using Memtest86+ (v4.x), Prime95 or other closest programs?:ohyeah:

First of all update BIOS to f7 then if that doesn't fix the issue try to find at northbridge temp and cpu just keep your Hand ceased and see if there is a maximum temp applied then replace the graphic card or psu and disable the auto restart within the safe mode. See if there is some software's or malwares or viruses in registry or some where and get if there is a blue screen and disable all overclock and provide the manufacture configurations...!!!!!!!!