Hi David,
some limitation exists with fixed power supply and 140G cards:
You can have a maximum of 2x140G cards + 1x40G card in slot 0/1/2 but not 3x140G cards
You can have a maximum of 2x140G cards + 1x40G card in slot 5/6/7 but not 3x140G cards
No particular recommendation for slots 3 or 4 (40G or 140G are fine).
Cheers,
N.