I just popped a Q6600 with 8MB L2 cache into my SC440 replacing an old pentium-D.
At the moment in the bios it shows up as a Q6600 but only shows 4MB L2 cache, instead of the 8MB it should show.
I have the latest bios version 1.5.0.
Also shows as this in the OS.
It's probably because that processor is not supported in the SC440:http://www.dell.com/downloads/ap/products/servers/en/PESC440_spec_ap.pdf
The following are supported:
Furthermore, the system supports up to 4MB of L2 cache.