The 6970 makes games run a treat. I've got a 6950 1gb and it makes my games run quite smooth (I'm playing 1600x1200- so didn't need the extra headroom). I'm a long time PC gamer, but I tried console gaming last generation. It's just not the same. Back to the PC now.
Not sure if it's worth it to you, but you could use something like this to fix your issue:
http://www.amazon.com/PS2-Keyboard-To-USB-Adapter/dp/B000BSJFJS
I think there is a known issue with the 6xxx series on the NForce boards. Maybe the problem was with the 6950 only. I don't remember where I read it though. If I find it I'll post back.
I got one of these. It really helps me:
http://www.amazon.com/Microsoft-Natural-Ergo-Keyboard-4000/dp/B000A6PPOK/ref=sr_1_1?ie=UTF8&qid=1310253168&sr=8-1
I'm using a AX750 with 1x6950 and 1x5830, and 1x 400gb 7200rpm hdd on a 780i w/a Q6600 at 1.4 volts. It consumes ~450 watts according to my belkin power measurement device. Hope that helps.
BTW, why the heck are you using a 6 core in an HTPC?
I haven't had an issue like this in quite some time, but it does happen sometimes. I had a Pentium Pro that would reboot if I installed a sound blaster 16. No matter what. Drove me crazy. I had to go buy one of the first PCI sound cards because of it. Glad you were able to get the budget...
Buy an h50, h60, h70 or h100 and overclock the snot out of your cpu. Then we'll talk about upgrading you graphics more. Oh, and get a better screen, too.
Not only the clock speed boost is going to help though, you'll also get the benefits outlined in previous posts (having 4 cores instead of two). You'll see a rather nice performance increase.
A company can become virtually invincible if they legislate themselves into business and can engage in predatory pricing. The barriers to enter the processor market are tremendous. The only reason that AMD remains competitive is because they have won lawsuits allowing them access to the x86...