My computers specs:
AMD 3800+
A8N-SLI mobo
2gb patriot ddr RAM
nvidia 7950gt
750w power supply

It started when my computer would randomly lose connection of my USB devices. Now my PC only starts 1 in 4 times and it usually only gets to the login screen before it freezes. If i get it to run I often lose USB connection and get strange sound glitches. I am almost certain it is a mobo problem and have replaced the CMOS battery and updated BIOS but nothing works. Is it fried?

Are you able to boot into Safe mode? To do this press F8 continuously at startup. Then select the option "Safe Mode" and press Enter. If you can get into Safe mode post back here.

Also try moving the RAM sticks from slot to slot, 1 at a time in each slot, booting the computer in-between to see if it is a bad RAM stick or RAM slot at fault.

well i tried 5 time it started 2 times and each one it froze as it was just loading my desktop. I swapped the RAM into all acceptable postions

if the pc is booting and you are not getting a BSOD, but instead freezes, this is pointing to the HDD, use a disk utility ( that will not destroy you data) to run a check also do you have an external HDD or IPOD connected to the PC?

no external HDD or ipod and when it boots it often will freeze up before it gets to the windows loading screen. Very rarely I can get it to work for an hour and then all devices lock up and the sound card emits a squeal. What disk utility do you recommend? As of now I cannot get past the BIOS screen.

Sounds to me as though the ICH (what would have been known as the south bridge in older sysyems)on your motheboard may have dry joints underneath it.
One of the many functions of the ICH is the USB controller. It is also one of the major central players in the running of the mobo.
In my job which has involved upgrade and repair of 1000s of motherboards on major industry leader contracts , intermittent problems such as the ones you are describing, are often attributed to poor connections under a BGA.
In case you don't know, a BGA is a chip where all the connections(solder balls) are underneath the chip itself rather than having pins around the outside like conventional chips. A dry joint is where a connection from the motherboard to the chip is damaged.
My experience is based on test and repar of motherboards and not sysyems
Please wait a bit longer and see if you can get any answers that point to possible system errors that you may have before writing off your motherboard.

i would bet money (cost of my new mb) its the power supply. have it tested save some money...