I take it you tried 8x400? Also, run your ram 1:1 (800) for starters. And don't use vmch at 1.75v. Unless you really can cool that, it'll cause more problems than not. Use 1.45vmch. You won't need more than stock 1.2vfsb either.

Set ram timings as follows for now: 5-5-5-15-5-42-3-11-7-13. turn off static read. run ram 2.1vdimm for now too, since you'll only be 800mhz.