I was looking at the Gigabyte website for the P35-S3L and the P35-DSR3 and on the memory support list, neither listed Crucial 1066 ram. Will this ram still run on these mobos?

not sure, i have a p35-ds3r and some crucial ballistx in 1066 i have'nt tried yet because i need to backup my computer before using. 800gb hd i ned to put on a 500gb hd... going to be tough.

The ram listed in the Gigabyte site and the rams that are tested and known to run in the motherboard. The ones that are not listed does not mean it's not compatible but just not tested.

Yeah, they just don't bother to test all the brands of RAM - either that or there's some nefarious product placement going on here.

I'm typing this from my GA-G33-SD2R with Crucial Ballistix PC2-8500 1066 2GB kit memory. Running fine at 1066.

Best thing to do is go to the Crucial website and put in the mfg/model of the mobo and they will tell you what RAM is compatible.

The board does support the 800MHz Crucial so I assume that they just haven't tested the 1066 yet - but cannot see why there would be a problem.

I'm running the P35C-DS3R with the 800 right now and I'm sure that when I looked that one was on the list.

i do have the ga-p35-ds3p and im using crucial ballistix tracer DDR2-1066 PC2-8500... and it work no problem

Same here...running Gigabyte GA-P35-DQ6 with Crucial Ballistix PC2-8500...no issues.