An old subject rears its ugly head - Neo Platinum + 6800 + Sata = no 3D. Help?

Question

I've been battling this issue for almost three months now. All of my problems started when I upgraded my hard drive to a Maxtor 6L250SO 250GB 16MB Sata hard drive. Coincidentally, only two days before I had upgraded my video card from an MSI RX9800Pro TD128 (which I never had trouble with) to an Nvidia 6800GT. For those two days that I ran the 6800GT on my old Pata hard drive, I was able to run 3D apps, although they seemed stuttery. As I said, I upgraded to the Sata hard drive, and had actually RMA-ed the old PAta hard drive, as SMART warned of failure. The point is that the Sata drive is the boot drive. Sadly, it wasn't until after I bought these nice upgrades that I learned of this forum and all of the compatibility issues with the NF3, sata drives, and the 6800.
So three weeks ago, unable to figure out why I couldn't run 3D apps, I rma-ed my K8N Neo Platinum. I received the replacement yesterday, and have spent the good part of 12 hours or so since then trying to make things work again. But it turns out I am right back to where I started before I rma-ed my mb - none of my 3D apps run for more than a few minutes. They all crash to desktop. I have read the stickies here extensively (not meaning to say that I've read it all or I know it all), but I am at a loss as to how to fix my problem.
my specs:
A64 3700+ Claw - no OC
MSI K8N Neo Platinum - bios 1.7, Nvidia 5.11 chipset drivers
2GB Crucial PC3200 DDR400 - no OC
eVGA 6800GT 256MB AGP - no OC, no FW, 81.95 drivers
Maxtor 250GB Sata 16MB (boot drive on sata port 3)
NEC DVD-RW & Asus CD-R on IDE1
Creative Audigy2 Value
One thing I haven't tried is moving the OS to an Pata hard drive (the one I got back from rma). Is it possible that booting from a non-Pata drive will fix the problem?
Is there anyone out there that can help me fix my problem or am I just screwed? Sadly it seems as though the only solution would be to get away from the NF3 chipset but I'm tired of throwing good money after bad. Please help if you think you can. Thanks.

Answer 1

Today I tried the rivatuner tweak found here:
Nvidia Forums
This didn't seem to solve the problem.
Then I tried this:
uninstall GART driver ONLY!
restart
download this driver pack
Guru3D
install the new GART DRIVER ONLY!
reboot
download this
PCI Latency Tool
DO NOT PLAY WITH THIS YOU CAN HURT YOUR COMPUTER WITH THIS.
install and change the latency on your 6800GT card to 64 aply and save (dont for get to set it up for load on startup)
reboot
now try your DirectX 9 games with this setup
also turn "ON" Fast Writes
This seemed to help some, but only in that I was able to play Doom3 for about 15 minutes, a record. It did not crash, I just ended the game, so i can't consider this extensive testing by any means.
The thing thaty really bothers me in all of this is that my problem seems to be more severe than everyone else's, at least from what I've read. Everyone complains about the "stuttering problem" with the NF3-250 & 6800 combo. My problem is that all of my 3D games crash (either freeze, CTD, bsod, or reboot my pc). Playing Doom3 today w/o crashing was a first since I got my 6800. That's not much consolation for me though, as my main game is BF2. Now in BF2, I can play the game for 5 or 10 minutes, but then the game screen freezes, and the game sounds get mangled and play in a loop. At that point I can't do anything with the pc but reboot.
So since it seems like I won't be able to fix the problem with my current hardware, I'm considering trying a different motherboard. I was thinking that I'd want to move away from the NF3-250 Nvidia chipset, but my hardware requirements limit the chioces drastically, and I don't want to buy a lemon. So my question is, if I were to stay with the NF3-250 chipset, is there any one board that stands out as being the least likely to have these issues? My buddy has a DFI Lanparty Ultra, and he is using a 6800 GT OC and says he has none of these issues. That sounds great, but I've also read that DFI's product support (bios and drivers) is even worse then MSI's and that scares the bejeebies out of me.