From the picture of the motherboard shown you can deduct the following:
In this PC you can thus actually put two S32PCI64 cards or two
FILAR cards. The 5 Volt slots are not usable for these cards.
there are four 64-bit, 5 Volt slots
there are two 64-bit, 3.3 Volt slots
the 5 Volt slots can only be 33 MHz
you cannot know if the 3.3 Volt slots are 33 MHz or 66 MHz
From the datasheet
from the SuperMicro motherboard
you can find out that the 3.3 Volt slots can be configured to run either
at 33 MHz or at 66 MHz.