" That's because Nehalem (Core i7) features Hyper-threading, which converts one core into two threads - 1 physical, and 1 logical.
Hyper-threading simply takes the unused portion of the core, and spin off a logical core off it. Therefore OS actually detects the CPU as 8 "cores". So in essence, it was an 8 thread machine vs. an 8 thread machine.
As for comparing between Core i7 and Core 2s, it really depends on the programs you are going to run.
If you're going to run games, chances are you won't see a big improvement.
However if you run CPU-intensive applications such as AutoCAD, or rendering programs, you'll see a significant improvement.
Now, if you're really considering multi-socket computers, then you should really take a look at Gainestown - Core i7's server part. "
as for the rest of the hardware, I'd take a lower latency RAM, CL7 or CL8 for better performance.
and then think about adding SSD, just my opinion.
Samsung Spinpoint F3 1TB and not the WD 1TB for better HDD as well.
Just so you know, the E5620 has HT as well, so 980X vs E5620 is 6 core/12 thread vs 8 core/16 thread. The E5620 is a Gainestown, assuming you have the correct name.
I would suggest a dual-CPU board with one X5650 (assuming that is possible) over a 980X, as you could later add another CPU. Other than that, I'd definitely recommend dual E5620s.
May I suggest a dual E5645 set up? They're in the same tier as the E5620s but are 6c/12t each giving you 12 cores/24 threaded for a reasonable price. The X5650 is just a little better than the E5645 - slightly better clock speed and better QPI, but at double the price of the E5645s.
I'm getting this setup for my Avid Nitris DX rig.
EDIT: I'd also suggest ANY Xeon over an i7 for CAD/Video editing work. People are too quick to forget that the i7s are still home use CPUs. Xeons are created to calculate and manage much heavier loads over a longer life cycle. That and dual CPU rig will always flatten a single core i7, Hyper Threaded or not.
Seems that the dual 5600 series out benchmarks i7s to me. I'm gonna go on a limb but.... 12c/24t > 6c/12t ?
EDIT: Also the rig at my office which is essentially the same as the one I'm suggesting has no performance issues due to two CPUs communicating to each other. That's a load of crap. @24Gb of ram that unit never goes over 48% memory even with heavy calculations.