Then you'd need a Case, Power Supply, Graphics Card, Hard Drive, So that'd be close to your budget and be an i7 solution that'd give you really strong parallel performance (something that probably gets taken advantage of heavily by your workload)
Xeon or Opteron will be your best bet, Server boards allow more memory then desktop boards.
To support 23 Gig you need ECC RDIMM, If you Non-ECC UDIMM (STD RAM for desktops) most max is 16.
With the Socket 1156 server boards support the Core i7-800 series and Core i5-700 series will only allow 16 Gig.If you go with a socket 1156 you must go with a xeon. Some boards have 4 Memory slots and some 6, If you go with the 6 slots you will still have to get 4 8 gig sticks.
If you go with the Socket G34 you can get 32 gig with non-ECC UDIMMs. The SUPERMICRO MBD-H8SGL-O has 8 RAM slots so you can use 8x4 Gig sticks.
Both setups use DDR3 so its cheaper to go with the AMD setup, The 8 4Gig sticks will run around $900-$1000 or the 4x8 ECC for $1200-$1300 just for RAM.