Ok, so there are several posts regarding the K9A Platinum MSI Mainboard with similar issues to mine, but I was unable to find something exactly the same or that could help me resolve my problem.

First off, here's the specs.

MSI K9A Platinum Motherboard
4GB Corsair DDR2 PC2-6400
Windows Vista Home Premium x64
Radeon HD3870 XT
Seagate Barracuda 7200 SATA 320GB
Logitech G15 Keyboard
Logitech USB Laser Mouse

I have been fighting with this thing all day long and im just frustrated and tired, so please bear with me. This machine has worked flawlessly on 2GB of ram for over half a year. Today I purchased 4GB of Corsair ram which is compatible with the Mobo (as listed on the MSI website). When I installed the ram, I could not get the PC to boot on 4GB, so I did some searching around and found out there were bios updates that fixed this, as it was a compatibility issue between the motherboard and vista 64 trying to boot with 4gb of ram.

I do not have a floppy drive, so I created a boot cd with the proper flashing files and flashed the bios with the latest version. The flasher said that the program was completed so I rebooted. At this point all I could get after the post was a blank screen with a flashing cursor. So I toyed with the CMOS a bit and rebooted a few times and finally got it to boot into windows (I had to disable the floppy drive in the CMOS). After a while I noticed that some things were running much better with the ram upgrade, however FPS in games etc was low (as in half my normal), and I figured something must have been up in the CMOS Settings, as it had reloaded minimal defaults after the flash.

So, I decided I would go and toy with the CMOS some more and try to tweak a few settings to up the performance. After I made a few changes, and rebooted with saved changes, I was stuck at the post screen, unable to enter the Bios, and unable to boot. After rebooting several times I decided to reset the CMOS via the bat-jumper on the board.

Now then, to the problem. After clearing the CMOS via the jumper, when I power on the computer, the post screen loads, and then brings up an error saying PS2 Mouse not found, then it asks me to use the keyboard --> Push F1 to run SETUP, or push F2 to load default values and continue.... The issue is, I have no keyboard functionality. Its saying push F1 or F2 to continue, but the keyboard does not work so I can not get past this portion of the POST. I have no PS2 Mouse available but I guess I'm going to have to get one tomorrow and see if I can get past this error message. I have tried multiple keyboards on the machine all with the same result. Does anyone know what the hell this kind of issue could be? Why would USB keyboards simply stop working with the Mobo after a CMOS reset? I have been searching the net for several hours trying to find a solution with none to be had. Needless to say, I have been jacking with this all day and I'm about ready to take my MSI board, rip it out, and toss it in the trash. Any insight to this problem would be greatly appreciated. Thanks!

-C

Could possibly be the BIOS not liking the keyboard.
When I was setting up my RAID I couldn't get the keyboard to work a few times (Logitech G11) which was a touch errrr problematic!
Basically having a crappy old keyboard spare is the best solution. I've had the same problem at work, and bunging in an old PS2 (ideal) or an old USB (not as good) is usually a solution.
Sorry I can't be more helpful, but I think it is a case of the BIOS not liking your keyboard.

Ok simple fix i had that mobo on last build, tiz very good bar that problem. It's an easy fix. I'm sure you must have a purple or green USB to PS2 socket converter. Simple as plugging k/b into that then into the purple PS2 slot.

In the BIOS it does have a 'Legacy Support' or summit like that so after you've plugged in via PS2 change it in the BIOS then you'll never have that problem again...until an unsuccessful o/c .

Ok guys, went and bought a PS/2 Keyboard today and was able to access the BIOS and get it all fixed... I'm posting from my machine using my G15 to type this message, woohoo. Ive been building PC's for probably 5-6 years now, but not a BIOS Expert.... Now I need to figure out some optimal overclocking specs for this board and my processor... anyone have experience with these?

MSI K9A Platinum
Athlon 64 X2 6000+ (3Ghz stock)

Thanks for the input Closed_Deal and LukeBird. I had to re-enable the USB Legacy support using the PS/2 Keyboard!

-C

Hehe your talking to an ex 3.5 Ghz AMD guy. Have a nose at my setting in this link my give you some hints:

http://valid.x86-secret.com/show_oc.php?id=282771

http://www.tomshardware.co.uk/forum/244862-11-6000