I build alot of dual xeon servers and the problem I see with the powersupply you are trying to use is the very weak +12v.
The standard chassis I use is a intel 5300 and its power supply specs can be seen here.
http://www.intel.com/design/servers/chassis/sc5300/You Power supply has alot of +5 but the cpu connectors (Where most of your power for that rig is going)
Will be +12.
When you are dealing with machines of the type, It always pays to get approved power supply.
(Call up supermicro, they are easy to get ahold of a tech how knows his a%@ from a hole in the ground)
Most likely you will need a EPS 2.0 compliant power supply.
I built a couple of large (24 250GB drives in each, check out the case..)
http://www.buildtoorderservers.com/ProductCart/pc/viewPrd.asp?idcategory=43&idproduct=215dual xeon servers with supermicro boards last month, and had to call in because of memory issues, Kingston swore up and down that it would work, but supermicro knew it wouldn't. They recommend the correct memory sku and all was well.
Looking at your board you are going to need the same memory.
DDRII registered ecc., must be installed in matched pairs.
and as above not all registered ecc memory is equal, because the 1gig sticks I had worked fine in Intel serverboards like the SE7520JR2 but not with the supermicro.
And btw which chassis are you mounting this in?
You know xeon board require special mounting brackets (The cpu heat sinks have screws mounted to them that screw through the mother board and connect to the chassis)
And good luck with your monster..
(and if I may ask.... Why such a beast?? It's very expensive and won't run much faster then just going with a p4 820..)
Later,
dabone