Have you tried emailing Focusrite directly? They have always responded quickly for me and would be the best resource (plus they seem to keep track of what doesn't work with what). There are six variables at play - MOBO, FW card, interface, FW driver, interface firmware, and MixControl version.
That article Jack linked is a good read, and I saw two things I didn't realize in it - "TI XIO2200A - tends to work with most systems, however there are known compatibility problems when used with Z170 and X99 motherboards." and "Please note that you need to be on the Standard Windows Driver to use the OHCI Tool. If you are on Windows 7 using the Legacy Driver please revert to Standard Driver..."
After seeing that second one I think I am actually on the standard driver vs. the legacy one. Their link is broken, and my VIA driver is from 2006 (6.1.7601.17514) - when I googled the legacy driver it seems to actually read "(Legacy)" at the end of the driver name, which mine does not have.
Edit: I just ran their OHCI tool and got these results:
OS: Microsoft Windows 7 64-bit Service Pack 1 [6.1.7601]
CPU(s):
Processor: Intel(R) Core(TM) i7-2600K CPU @ 3.40GHz
Physical: 1
Cores: 4
Logical: 8
L1 Cache: 32 KB (8)
L2 Cache: 256 KB (4)
L3 Cache: 8192 KB (1)
Installed RAM: 8159 MB
Microsoft 1394ohci.sys [6.1.7601.17514]
Microsoft ohci1394.sys [6.1.7600.16385]
Microsoft 1394bus.sys [6.1.7600.16385]
Looking for OHCI 1394 Host Controllers...
1:
Vendor : (1106) VIA Technologies
Chipset: (3044) VT6307/VT6308
Revision: C0
Status : Active
Details:
Subsysten VendorId: 1043
Subsystem DeviceId: 81fe
Max # isoch Rx contexts: 4
Max # isoch Tx contexts: 8
Max 1394 Speed Capability: S400
Support: Compatible, no known issues.
Done.