RAM cracking under OC pressure

Okay I'm still pushing my CPU faster and faster, my X2 Brisbane 1.9GHz is up to 2.7GHz (on stock volts woot!). I'm running a 284MHz bus X 9.5 multiplier. I have my RAM divider at DDR533 which seems to be something like a 2.66 multiplier which puts my RAM at 755MHz. Up until today's OC I have not changed my memory timings from 4-4-4-12 T1. Once the FSB was upped to 284MHz I was forced to use 5-5-5-15 T2 timings or it would hang on boot and then default my RAM speed to 533Mhz. Honestly I have not tried 4-4-4-12 T2 timings yet but my question is why if the RAM is made for 4-4-4-12 @ 800MHz, why is it forcing me to use higher timings even though the total speed is under 800MHz? What else is going on that is causing this?

Crappy on-die RAM controller. With AMD, that can mean you're forced to get another CPU!

Crap, and the cores are doing so well over clocking. Does more core voltage effect the controller at all? Is there anything else I can do to effect the controller?

Any other theories or is this most certainly the issue?

Well the controller couldn't be having too hard of a time. Today I bumped the HT to 286MHz (the cores were just under 2.7GHz @ 284MHz and now are just over 2.7) and I set the memory to DDR533 divider with 3-3-3-9 T2 timings. It seems that the T1 was too much for the controller to handle. If I am not mistaken hasn't this been a running issue with AMD processors?

I know the T2 kills performance over T1 but I wonder if I can make that up with a higher HT and hopefully keep these timings.