Keyboard, mouse, and monitor don't work and PC freezes.
So my computer wouldn't start. Fans and lights would turn on, keyboard mouse and monitor would not. Determined that there was a bad stick of RAM. Put in new RAM. Continued to do the same thing if I had two sticks of RAM in. I replaced the PSU and now it will get to the Windows 7 loading screen, but with two sticks of RAM in any combinations of the slots, Windows will freeze. Any single stick in the second slot will allow the computer to run fine. Does this mean I have to replace the motherboard?
That's some great detective work. Hard to believe three out four slots could fail...I'm actually still skeptical. Short answer, no, you don't need a new motherboard if the single channel works fine. But if this is a recent purchase you may want to return/rma. If so, then it goes without saying definitely do it. If not, dual channel would be optimal, but if you're just doing internet browsing, word processing, and light gaming it's fine.
I used four different sticks of RAM to do the tests. All were 1333 MHz DDR3 (which is what was in there to begin with). Two from a different computer and two from a new computer. Again, trying every slot 1 at a time, the computer would only boot and stay on with the RAM inserted into the second slot. If RAM was inserted into a different slot, it would either not boot (third and fourth slot) or freeze upon booting (first slot). If additional RAM was added, it would freeze if it was in the first slot, not start if it was inserted in the fourth slot, and act as it would with RAM just in the second slot (but it isn't recognized by Windows). The computer is about 4 years old.
It's running/supposed to be running
8GB of ram (4GB for now)
450 Watt Coursair 80 plus bronze certified PSU
ASUS xxx chipset with integrated graphics
NVIDIA GTX 650 (integrated ATI graphics for now)
AMD Athlon II x2 2.8 GHZ
*edit* It should be noted that I'm doing audio editing/recording on this using programs like Fruity Loops. The extra RAM really makes a big difference. I won't be too disheartened if I have to replace the mobo/processor. A nearby store is selling an AMD FX-6300+low/mid end mobo for $120 before taxes.