I have to admit that like you I'm at a loss to explain why your getting this problem... You say that you flashed the bios to the latest version...yes?
Ok...I've been looking through google and it seems your motherboard may not like running your RAM at the default speed of 1600 at first. You may have to run it at a lower speed until you've got it running ok.. I copied this from a review in newegg:
Pros: Board runs solid and stable, with only a few hours of tweaking I was able to get my i7 920 up to 4.0ghz and my memory at 1600mhz. Also, the onboard cooling solutions is very well designed. Bios flashing is also quite easy, and there is a lot of support for this board at rebels haven web site.(link below)
Cons: The early bios releases didn't support memory speeds of 1333 or 1600 with a 920 or 940. Later releases have fixed that issue but there is still a moderate amount of tweaking required to hit 1600mhz on the memory.
I found this thread which may help:
Link Removed due to 404 Error
Here's a site dedicated for that mobo:
http://www.rebelshavenforum.com/sis-bin/ultimatebb.cgi?ubb=forum;f=49
Sorry I can't help you with an exact solution but perhaps the answer lies in the above links...
In the meantime I'll keep my eye's open for a solution..
Good luck and please let me know how you get on..