Why not buy a x5660 for 85$ and over clock it to 4 ghz. Or even the x5675
It is a very easy safe overclock that will in most cases run under 1.3v.
1.35 is the Intel max voltage for those chips.
I say x5660 because you will be able to run a 23x multiplier with a 175 bus for 4ghz
Or the x5675 will be the 25 x multiplier.
The Classified3 SLI3 and FTW3 should run them with out a hard mod needed.
Here's a list for Evga mobo's that support -EP Xeon's & the minimum Rev. required to run them.
I got the list from an other forums x58 1366 xeons very long thread.
E757 - Rev. 1.1
E758 - Rev. 1.2
E760 - Rev. 1.1
E762 - Rev. 1.1
E767 - All
E768 - All
Most of the Rev. 1.0 boards do need a hard mod in order to use -EP Xeons.