MEMORY WONT RUN AT ADVERTISED SPEED

I wonder if, like the older P35, the P45 has a problem with RAM that is intended to be clocked by default at higher than DDR2-800?

...I will content myself with sticking to RAM that operates at its advertised timing on the JEDEC standard 1.8V.

Not sure what you mean by running it at 1:1. First since it's a brand new build I had everything set to AUTO in the cell menu. It picked the 1066 mem speed which will not let the boot get past the bios screen. I turned the speed of the mem down to 833mhz and the machine works great.
My question is.....if the mem I have is rated at 1066 and the board accepts faster then that, why can't I run it at that speed. I tried 2 different MBs and 2 sets of ram.

Your problem is the Patriot memory. It is not that good. I had Patriot DDR2-1150 that would not run at the specified 5-5-5-12, 2.3V. I tried everything I could think of, but it wouldn't run. Untill I set it to just 2.0V, then it worked. It didn't like the higher voltage, even though that's what the specs said.

So try using 2.0V and see if it works for you. Also manually set the timings to 5-5-5-15. Test each stick separately. You could have just 1 bad stick of ram.

ITS MSI DONT EXPECT MUCH

second there right that 1:1 ratio with lower memory timings is far better, anything higher is useless, and with memory, your better off setting everything manually (timings, voltage and ratio's) so you know how its running etc.

Mushkin and A-Data both have some decent DDR2-800 that runs at its advertised timings (5-4-4-12 and 5-5-5-18, respectively) on the JEDEC standard 1.8V. The difference in timing will probably not be noticeable in actual use, but the Muskin can probably be manually oc'ed higher if you want to do it.