I built my system about 9 months ago with two 4GB sticks of Corsair Vengeance RAM. They are running currently at 1600MHz and have timings of 9-9-9-24. I want to add another 16GB(two 8GB sticks) of the same line of RAM from Corsair but the timings are different, 10-10-10-27. I want to know if it is possible to have two different timed sets of RAM in one system.
yes it is possible but you might run into some issues with stability if you don't take proper steps to ensure stability.
if you place the 2 4 gig sticks in the same channel and the 2 8 gig sticks in the same channel it should be fine. and if you loosen the timing of the 4 gig sticks to match the 8 gig sticks it would be even better. depending on your motherboard this should not be hard to accomplish.
Yes it'll work, but likely your dimms running at CL9 latency will run at a slower CL10. Since this is only DDR3-1600, compatibility shouldn't be a huge problem.