I'm building a new rig with i5 2500k Sandy Bridge processor and I want some help regarding choosing the memory sticks. I need to choose between the Corsair Dominator 4 GB kit (2GB X 2) or the Corsair Vengeance 8 GB kit (4GB X 2). Which one should I go for? The Dominator's are more pricey but I'm ready to pay a little more if it is worth it.
Also, I have read that the the i5 2500k needs 1.5v memory sticks and that Vengeance fits the bill better there and using the 1.65v Dominator memory sticks can end up frying the CPU's memory controller?? Is this true because in that case I'll just stick to buying the Vengeance sticks.
Other system specs of the rig:
Mobo; Gigabyte GA-P67A-UD3R-B3
GPU: Powercolor HD 5850
PSU: Corsair VX 550
Audio Card: Asus Xonar DX
Storage: 60 GB Mushkin Callisto Deluxe SSD + SG Barracuda's
Case: Lian Li A70F Full Tower
1.65v ram is the same as 1.5v ram, except that it has been binned, and can be overvolted to 1.65v to get higher speeds. 1.65 is OK for sandy bridge, but no more, or you will permanently damage your cpu.
The sandy bridge memory controller is very good. It is able to keep the cpu fed with ram data so well, that faster ram or better timings do not make much real difference. Real application times, or gaming FPS may improve by 1% or so with faster ram. Not much worth it to me. Synthetic benchmarks will show a big difference, but unless you are a record seeking overclocker, it does not make much sense to pay much more for faster ram.
Also, do not pay more for fancy heat spreaders. They are mostly marketing. Sometimes tall heat spreaders will interfere with your cpu cooler.
1.5v ram will run very happily without any heat spreaders at all!
Just get a 8gb kit (2 x 4gb) of 1.5v ddr3 1333 ram. 1600 is usually not much more, but there is no need to go for better timings or speed.
It might be good to check the corsair configurator and get a list of their parts that are compatible with your motherboard. If you should ever have an issue, you will then get help if your ram is supported.