Timing definition

hello

i am using a dell 435t-9200. it came with the standard 3 gigs of ddr3 dimm's.

i am considering upgrading my ram to 12gb using corsairs. the timing specs for the corsair are 7-7-7-20.

i believe my system is 8-8-8-24. but can't swear to it.

will this work out of the box? or will some tweaking be required? will Windows 7 just make it so?

also there are voltage considerations. will i have to tweak the bios?

all help is appreciated.