Does a SP94 HS fit in this MB?

Does the SP-94 thermalrigh heatsink fit in a Abit IC7-MAX3 MB.

Yep, it should.

Just making sure the plastic enclosure doesn't get in the way.

Yes it does. Numerous people use this setup.
congrats on a great buy!

it should fit

and, holy crap! that max3 board looks a lot better than my IC7-G!

SP-94 Socket 478 Motherboard Compatibility Information
Manufacturer.... Chipset....... Model
Abit

Intel ..................865PE........... AI7
Intel ..................875 ...............IC7-G
Intel ..................875 ...............IC7-Max 3

SOURCE

That mosfet cooling duct its pretty damn cool, id have to say.

Thats more like a gimmick actually cos I don't see any improvements with my system's stability. Frankly...I think that the IC7-G is a much better buy than the Max3 unless you really need the 2 extra SATA ports. Max3's vDIMMs are also pretty crap...you can read about it in Abit's own support forum.

No worries about using the SP94 on your mobo..nissmo300. I am using it now and the heatsink's performance is SWEET! Idling at 32 degress but since I am located in the tropics, you'll probably see better performance than mine.

Regards