As per eVGA's webpage max supported ram is 1066. But with OCing, you can run it at 1200 and higher. I only ran it to 1200 on my Ballistix. But I would recommend the G.Skill DDR2 1000
kit for $110. 2 ram modules puts less strain on the board's memory controller, so 2x2 is better then 4x1 on the NVIDIA chipset. Another plus to the ram is it runs at 2.0v - 2.1v. The Ballistix run at 2.2v, which has been known to cause issues with NVIDIA chipsets.
As for the ram timings. The ram at 4-4-4-12 read/writes at a rate of 4ns, where as the 5-5-5-15 timings read/write at a rate of 5ns. So you will actually get better performance with CAS 4 vs CAS5. The problem is, as you increase the memory's overal speed, the timings nedd to be loosened for stability. ie. 4-4-4-12 needs to be loosened to 5-5-5-15.
Another note about your baord, the ram can be run unlikned. So you can set it at whatever speed you want and the board will auto config a divider to run it at. Intel chipsets on the otherhand have to run specific dividers, which can prove more tricky to find a stable balance between FSB, RAM and CPU overclock.
You can find the list at eVGA's website on the support page under Motherboard Memory Support:
eVGA 780i/680i Series Memory support
*other memory modules may also work, the following are known compatible memory kits*
SLI Ready memory
Above 1066 MHz(Above PC2 8500)
1066 MHz(PC2 8500)
900 MHz(PC2 7200)
800 MHz(PC2 6400)
Above 800 MHz(Above PC2 6400)
Patriot PDC21G8500 ELK
800 MHz(PC2 6400)
Team Xtreem PC2-6400 800MHz 3-3-3-8
Team Xtreem PC2-6400 800MHz 4-4-4-10
Geil Ultra GX22GB6400UDC
Super Talent T800UX2GC4
667 MHz(PC2 5400)
PQI 5400 Turbo
Muskin xp2 5300 2x1gb
533 MHz(PC2 4200)
PQI MAB412UOE 512MB DDR2 533
OCZ DDR2 OCZ2533512V
Page Updated: 12/19/2007
edit: When you get your ram, set them to unlinked
(set to linked
in this pic) and then set the Actual FSB (QDR), MHz
to the memory's specs (it is in blue and not selectable because I have it set to Linked and synced).
Make sure to also set the proper memory voltage and timings.