Memory Problem ? ?

I recently added another 2 gig of memory in mys system to take it to 4 gig all up...same brand and type...however when I open up Gigabyte "Easy Tune 6 " programme and go to the memory section it incurs an error screen and shuts down the programme...also when I open up CPu-Z I don't think it's reading all 4 memory sticks correctly as some are showing at 5-5-5-18 and they a re 4-4-4-12 sticks...

These are the ones...http://www.corsairmemory.com/_data [...] 6400C4.pdf

I have gone to the bios section and set the memory section to "manual and input those timings as the standard profile shows it at 5-5-5-18 and increased the voltage to 2.1 from 1.8 where it is at the moment however it doesn't boot up into windows properly after...

If I leave everyhting standard it does and XP does recognise 3.25 g of memory but I want to run these at the level they're supposed to be made to run for...


System specs
e8400 @ 3.0 ( 9 x 333 )
4850 gpu
500 g HD
650 True power PSU
Gigabyte EP45-DS3L M/B


PS I get better scores by in 3dmark 06 using the easy tune function on the motherbard to overclock than if I turn it off and overclock thru the bios...