The S2912 (not "-E") will support the AMD Quad Core Barcelonas with the v4.00 BIOS.
Why? - On a binary file compare, both the downloaded Tyan s2912 and s2912-E v4.00 BIOSes are IDENTICAL (actually only the zip file package names are different, the files inside are not).
Also - I have a S2912 (not "-E") with v4.00 BIOS that I have recently built with (2) Quad Core AMD 2347 CPUs running without a hitch!
So, go for it.