I dont know if this can help you. I dont know on the OEM products that have Intel Chipsets. But i do know on the Intel Products.
Let me summarise your query:
You need a system that has these features:
1. Single X5492 Quad core Xeon Processor 3.4 GHz (1600 MHz FSB)
2. Intel 5400 Chipset
3. 32 GB (800 MHz FSB) or 16 GB (800 MHz FSB)
I know that there is an Intel Server Board which is the Intel® Server Board S5400SF. Actually it does support the Quad Core Xeon CPU X5482 (3.2Ghz, 1600Mhz), provided that you have the latest bios version R30, probably in the future it will support the Xeon X5492,as it has the same features. (You can contact Intel Customer SUpport for enquiry)
Now regarding the memory, it does support up to 128GB of memory. It supports FB DDR2 800Mhz.
800 MHz FBDIMM Compatibility Note:
The use of 800 MHz FBDIMMs is only supported with Multi-Core Intel processors that support a 1600 MHz front side bus. Using these FBDIMMs with processors that support a lower frequency front side bus is not supported on this server board.
And finally it has the Intel 5400 Chipset.
Website to check:
CPU Support: http://www.intel.com/support/motherboards/server/s5400SF/sb/CS-028455.htm
Memory Support: http://www.intel.com/support/motherboards/server/s5400SF/sb/CS-028456.htm
Hope this may help you a bit.