That sounds like a dead clock battery. If you open up the top panel on the programming side you should see a cr 2032 on the top of the motherboard. Take it out and replace it. You should be able to find it at any radio shack, home depot or maybee even a Walmart.
Lee is almost certainly correct. Just like a desktop PC, the motherboard has a CR2032 lithium button battery that keeps the clock running when the system is powered off. When this battery dies, the console will start to lose time. I'd start by replacing this battery.
where the onboard graphics card wouldnt work but the other graphic card would, the clock didnt go ether, it was the battery on the mother board. i also had to reset the bios, witch you should contact the help line to do it right, as you can make things go bad very fast if you dont know what your doing!!!
It's a fairly safe generalization to say that any time a computer is losing system time replacing the motherboard battery is a good place to start.
Replacing the battery isn't difficult, but you should verify that all of your BIOS settings are correct, since the battery is responsible for keeping these settings saved on the board. We have a instruction document for replacing the battery and verifying the BIOS settings that can be downloaded from the Flying Pig Systems web site: