It appears that my install of XP Pro x64 was suspect and somehow responsible. I also could not get it to boot in AHCI mode. I decided to to a fresh install, this time I made myself a nice little nlite package using my XPProX64SP2 disk and added the AMD SATA AHCI drivers, Catalyst 11.6 Display drivers/SB drivers, my USB wireless drivers, and my HDMI sound drivers along with Seraph's Post SP2 update pack and IE8 add-on pack.
So far so good, it boots everytime and all I had to update from the M$ site was the .NET installs (I couldn't find a good X64 update/addon version and it still only took a short while to bring .NET up to full speed). It easily booted at auto 5-5-5-18 2T, and I am able to boot at the EPP settings of 4-4-4-15 2T, I will run Prime95 tonite or tomorrow to check for memory stability at those timings. I wasted so much time trying to troubleshoot this I wish I would have just went for the fresh install at the outset.
But at least I learned how to use nlite so it wasn't a total waste
Thanks for your help
edit: Prime95 for almost 3 hours at 4-4-4-12
2T and not a hiccup, even better than the 4-4-4-15 ratings in the EPP. i guess I didn't have to loosen timings after all. So far so good!
edit2: Prime 95 overnite at 4-4-4-12 2T and no errors. Here I was so obsessed to get all 8 GBs of memory functional that from what I see now unless I plan to do some major crunching on this box it won't even be used. Prime95 (even with blended/lots of ram tested setting) never went over 3GB or so of usage, and that was with an Avatar 1080 mkv rip running on MPC-HT and FORTY ( count 'em, 40! ) windows open in Firefox
. Since this is just my HTPC running a PH2x2-550 unlocked to 3 cores I am REALLY running overkill on this box.
Oh well, at least I know the memory it torture tested and runs great, I just may go ahead and sell one of the 2x2GB kits. Live and learn, eh?