ASROCK mobo help

I own 2 AS rock mobo's the AOD790 and A780gxe. The promblem that I have is that, They will not run 8 gigs (4sticks) of corsair 800 memory at 800. I have changed the voltage up to 2v. Manually set the timings, set the the memory from auto to 800. But none of the boards post after saving. When they do the memory gets set to 200. I can run the 4 sticks at 667 no problem but will not overclock. I have run memtest with a stick at a time, as well as all them. But it never shows any problems. I have contacted ASrock and they have told me to RMA my boards. I dont want to deal with RMA's. I can run 3 sticks (6gigs) or less at 800 and overclock to over 950mhz and stable with little voltage bump.
I was wondering if any one has had similar problems? Or just some imput on what im doing wrong? I find it hard to belive both mobo's are crap even if the are I will not RMA. They run fine and I dont really need 8gigs. But I think I might be doing something wrong. And both mobo's have latest bios.
Thanks

I have an ASRock 780G board and run 2x2 gb of DDR2 1066 ram. I have found that my board does not like the higher voltage necessary to run the ram above 200 mhz. fsb. If I set it above about 1.9v I start having boot problems or instability. I tried many combos of timing at 2.05v (mfg. rated voltage for the 1066 speed) but could not get it stable. Finally, I lowered the voltage on the ram and it would boot into Windows and even run Prime95 for a few minutes at 1066 if I chose the "Relaxed" option in bios. Prime aborted after about 15 minutes and I think it was because the ram need a little more voltage to be completely stable. I returned to 200 mhz. fsb and tight timings at 1.9v and its good to go. Now I realize you are not trying for 1066 speeds and your issue is amount of ram and not speed but my point is I believe the ASRock board electronics (v regulators/caps) supporting the ram are a little weak. They seem to be quality boards in most other respects, though.

i have the AOD790 board, similiar problem, it will run with 8 gigs @800 (using OCZ PC8500 stuffs) just fine, and will boot and run the 1066, but errors abound no matter what settings are used in the bios...similiar problem with an M2R from DFI in the mems department, abandoned the board because of other problems though (PWM temperature spikes out of nowhere)....

this is not uncommon with AMD stuffs, it is what it is...

i gave up and now just run 4 gig, with some tweaks...if you really NEED the 8 gig, 667 is your option, just like I have the option to run the PC8500 stuffs @PC6400 settings......

laterzzzz...........