It varies. I have a Dell Precision 490 (that I'm selling btw) that has 8GB DDR2 RAM, RAID10 on 4x 400gb seagate SATA-1 HDD with 2x Xeon x5060 CPUs (dual-core @ 3.2ghz and hyperthrad). The DDR2 is slower than DDR3, the X5060's are 65nm tech vs. an i7 (or comparable xeon at 32nm tech and the sata-1 hdd is obv slower throughput at 1.5gb/sec vs. 3.0gb/sec. The P490 @ 3.2ghz & 8GB ram benchmarks almost the same as an i7 @ 2.66ghz with 9gb RAM. They give & take when you do a battery of benchmark tests. The dual-cpu boxes are cheap & very easy to come by and you'd be hard pressed to build an i7 box for the $600 I'm trying to sell this P490 for. In real life applications you'd be hard pressed to tell the difference. The thing is that the 2x CPUs each have their own dedicated cache so it ends up being pretty similar. Here is a dual-core Xeon x5160: http://www.cpubenchmark.net/cpu.php?cpu=[Dual+CPU]+Intel+Xeon+5160+@+3.00GHz and here is a Q9650: http://www.cpubenchmark.net/cpu.php?cpu=Intel+Core2+Quad+Q9650+@+3.00GHz The numbers are very similar even in the raw benchmark tests which heavily favor the newer architecture (intentionally). The difference is you can get a fully built box for 1/3 to 1/2 the price that's 90% of the normal benchmark and it'll perform in real life almost identical. Plus it'll be more configurable. Dual Xeon e5450 (2x cpu @ 4cores each, non-HT so 8 real cores): http://www.cpubenchmark.net/cpu.php?cpu=[Dual+CPU]+Intel+Xeon+E5450+@+3.00GHz vs. i7 950 Quad with HT (4 cores + 4 virtual cores): http://www.cpubenchmark.net/cpu.php?cpu=Intel+Core+i7+950+@+3.07GHz The 8 logical cores kill the i7 but you get the idea. They all end up about the same and with dynamic benchmark testing (like single vs. multi-threadded apps and CPU cache testing) you really find that they are about the same. The biggest difference I've found is in the power consumption - the newer stuff consumes much less power. The reason why you have such a difference is because these things overlap - you get different architecture (65nm vs. 45nm vs. 32nm, etc.) and that is the biggest difference. Its very hard to find an apples to apples comparison (quad core with HT vs 2x dual-core with HT both 45nm). The reason why the xeon's are so expensive is because you can pair them up and for today's technology you can get twice the horsepower of a non-xeon. The other nice thing about going the dual-socket route is you start dealing with superior hardware (server grade vs. retail/consumer grade). ECC or FB RAM, enterprise or server NICs & RAID & HDD, etc. its just better IMO.