You are most likely after one of the below solutions:
- 2 x Xeon 5100 (2 x 2 cores)
- 1 x Core 2 Quad (1 x 4 cores)
- 2 x Xeon 5300 (2 x 4 cores)
I can help you with this, as I've used Tyan, etc gear before and understand the Registered, ECC, and/or FB-DIMMs and 'workstation/server' chipsets on the board of which you speak. (and several of which you haven't, but may want to look at).
Core 2 Extreme QX6700 is covered here:
http://www.anandtech.com/cpuchipsets/showdoc.aspx?i=2866
Quad-Core (2 x 4 = 8 way) Xeon E5300 article:
http://www.dailytech.com/article.aspx?newsid=4914
The Xeon 5100 / 5300 are covered here on the Intel site:
http://www.intel.com/products/processor/xeon/index.htm
8) Bear in mind the 5100 / 5300 both use the Core 2 Micro-architecture, they just permit 2 sockets, each with 2 or 4 cores, for 4 - 8 way computing - typically with 8 - 32 MB L2 cache.
You may also want to check out:
::TyanPSC:: (Personal Super Computer)
http://www.tyanpsc.com/ - Link to TyanPSC site
http://www.tyan.com/ - Link to Tyan site
ftp://ftp.tyan.com/typhoon/TYAN_Typhoon_512K.wmv - Video - May need to right-click, then save as... / download before playing - It may not work with a single left click.
Despite what the video says their latest model will provide 256 GLFOPS, using 40 x 1.6 GHz Xeon (Core 2 based) cores.