[Beowulf] power supply/chassis for Opteron-based node

[Mikhail Kuzminsky]

I looked to reccomendation of power supply/rackmount chassis for 
Supermicro and Tyan dual Opteron motherboards based on nVidia Prof. 
2200/2050 chipsets (for example, Supermicro H8DCE-B). The recommended 
power for power supply is about 650 W (or higher), what looks as too 
high for our conditions.

We will use 2 or 4 GB DDR333, 2*Opteron 248, 1 x HDD 10000 RPM, 1 x 
Infiniband DDR (Mellanox) HCA per node (plus minimal PCI graphic card,
&CDROM). Currently (w/AMD chipset, for 2 x Opteron 244) we work 
w/cheap Chenbro chassis (4U) having only 420 W power supply. 

I understand that it's possible to calculate relative exactly the 
power requirements (ampers for each voltage levels), from TDP etc, 
but:

what is typical power of power supply used "here" - by beowulf 
community members - for close configuration of nodes (not 1U)? 
BTW, what is good cheap chassis alternative for Chenbro - AIC/T-Win ? 
what else ?

Yours
Mikhail Kuzminsky
Zelinsky Institute of Organic Chemistry
Moscow