around $2k budget

[tokyoduong]

http://www.anandtech.com/bench/Product/99?vs=551
here you go.

Looks like it will be as fast as a 3770k if you do some mild OC.
Not worth the upgrade cost to me. But see for yourself. OC is all you need right now and should last you 1-2 more years.

 

[Drmark]

I got my Alienware in 8/18/09 and they had that 975 back then. I just figured it was out of date and time to move on. I got 3 sticks at 1333 of Ram and bought 3 at 1600. Might it be better to dump the 3 1333 and replace them?

 

[tokyoduong]

I got my Alienware in 8/18/09 and they had that 975 back then. I just figured it was out of date and time to move on. I got 3 sticks at 1333 of Ram and bought 3 at 1600. Might it be better to dump the 3 1333 and replace them?

Yes, if you're running dual channel then you need identical RAM.

 

[Aquinus]

Yes, if you're running dual channel then you need identical RAM.

You don't need identical DIMMs. More often than not a machine will work with not just different speed DIMMs but different sized DIMMs. Synchronous dual-channel (or your case, triple since you're running an skt1366/X58 rig, is really the only thing you have to aim for. The best way to do it is with all the same DIMMs and ideally the same speeds and clocks, but a computer is usually good enough to downclock your memory to the slowest DIMM installed. So as long as you keep the same sized DIMMs per each channel, dual channel should work.

There are sometimes weird cases where it doesn't but more often than not you can mix similar DIMMs and in lesser cases different DIMMs but the more different they are the harder time you'll have running them together.

Ideally all the DIMMs should be the same size and speed if you don't want any hassle with mixing them, but they can be mixed... just don't expect it to run as well as DIMMs that are all the same.

I got my Alienware in 8/18/09 and they had that 975 back then. I just figured it was out of date and time to move on. I got 3 sticks at 1333 of Ram and bought 3 at 1600. Might it be better to dump the 3 1333 and replace them?

If you do replace any DIMMs, replace the 1333, but don't replace them just because of the speed. If you need more memory then it's a good time to do it. It also depends on what you have for memory. It's really the only components you didn't tell us about other than one is 1600 and the other is 1333.