I'm using dual channel ram, so if one goes then they're both useless right?
No. They work fine separately. Dual channel is a function of the motherboard and not the chips themselves. So if one goes the other can be used by itself. By itself it won't give you the extra speed of dual channel but it will still work fine.
A cold boot is when you turn off the PC and then turn it back on, as opposed to a reset or restart which are warm boots.
Your problem is very likely either mobo or power supply. I would not assume it is mobo until you have checked the power supply. This you can do by swapping in a known good power supply. You can always buy one and then return it if that's not the problem. Sometimes they fail part way, which can explain why some things are working and others are not.
You can always return the motherboard but then you could be wasting a lot of time and effort if it turns out to be the power supply.
As deuce pointed out above many generic power supplies are cheap and underpowered, the watt rating is very misleading. Without going into a long explanation the only way to be sure you have an adeqaute power supply is to buy a quality name. Antec and enermax are popular brands at retail stores and can usually be counted on. Just don't get an entry level Antec, get one of their better models. Be prepaired to pay $75 or $100 or more for a good power supply. Perhaps you can find one on sale or with a rebate. Buy one and if that's not the problem you could either return it for a refund or else keep it so you don't have to go back to that generic model.
KNOW THIS
The high end parts you have on your PC (8800 and quad core 2) are POWER HUNGRY and REQUIRE a quality power supply. If you go and pick up a retail power supply get something like an Antec or Enermax rated 600 watts or more to be safe. That may or may not be overkill but if it is a little overkill you will be prepared for future expansion.
As deuce pointed out that generic power supply is VERY suspect at this point.
You could be wrong about the power supply being generic, it might be ok, Take a look at it and read off the name and watt rating and also tell us what it says about the amperage on the 12v rails, it should spell this out on the label.