Jim Roseberry
The 4-pin molex power connection on Firewire controllers is to provide bus-power.
If you don't plan to use bus-powered Firewire peripherals... you don't need to connect it.  

 
I see. I do have the power supply for the Saffire, never used. Would there be a performance increase?
 

57Gregy
I see. I do have the power supply for the Saffire, never used. Would there be a performance increase?

 
You won't see a performance increase (as in lower latency)... but you might notice a fidelity difference (with 48v phantom powered mics).

Gotten to the point where the FireWire card is never connected. Device manager sees it, but reports that it's not connected. The Saffire's lights are lit, though.
Previously, a restart or 2 would enable it, but now it remains unconnected.
I guess I'll pull it out and reinstall and see what happens.

PCIe Firewire controllers are short x1 cards.
It doesn't take much for them to get just a smidge out of position (not making proper contact).
If this happens, re-seating the Firewire controller usually does the trick.

I just got this one:
http://www.amazon.com/gp/product/B002S53IG8?psc=1&redirect=true&ref_=oh_aui_detailpage_o05_s00
It works great with my old Presonus Firepod.  Note that I am on Windows 7 64-bit.  No Windows 10 drivers.

I happlily use 2 Mackie Firewire interfaces on 2 different DAW's - an old 1200F and a newer 1640i FW mixer/interface.  Both work great.  And I use the cheap Siig TI-chipset Firewire from NewEgg.  All is well.
 
PS - If you're having trouble with your FW card, I sometimes spray a little DeOxit on the connectors when I reinstall a funky PCIe card.  Works wonders, but I live ina very salty and corrosive environment.

Revisited this conundrum this week. Reinstalled the card and the device manager still doesn't see it. Clicked the 'check for hardware changes' and the 'show hidden devices' buttons several times and it doesn't appear.
So I removed it and installed it in the other expansion slot. Same story.
It's like the connections in the case just disappeared, like my DVD/CD drive did after the Win 10 update, an update that will live in infamy.
Is there something that needs to be done besides installing? Enabling something in BIOS?
I like the Saffire, but the Scarlett 2i4 looks pretty good, if and when the music computer does finally kick the bucket as it's threatened to do a couple of times in the last few months.

I'm using the SIIG Firewire card. I just put it in my brand new PC two weeks ago in order to interface with my Motu. I needed to get a SATA to old-style power adapter from NewEgg as the card wants the old style power connector to power the Firewire bus. My PC only supples SATA style power connections - the card came with an old-style to-old style Y-cable power adapter
 
SIIG-2-Port-FireWire-1394a-PCI-Express-Card
SATATMLP4F-12 Power Adapter Cable
 
It's working fantastically, and it's at a bargain price.

I have the molex connector attached and it powers the Saffire (the lights come on).
But the firewire card is not recognized by the computer. Previously, it did show up in the device manager, but "wasn't connected to the computer" according to DM.
Now, it doesn't even appear in device manager.

57Gregy
Is there something that needs to be done besides installing? Enabling something in BIOS?
...

Normally, no.  Unless you have somehow disabled the FW in the BIOS.  Wouldn't hurt to check.
 
Was the Saffire connected when you installed the drivers?  That can cause problems.  If it was (or you don't remember), it's worth uninstalling/reinstalling the drivers.  First make sure to physically disconnect the Saffire (or if it has a power switch, just power it off). After installing the drivers, reboot.  Then reconnect or power on the Saffire.
 
One other thing to try:  Clean out your registry with something like CCleaner (I use JV Power Tools for this, but if you don't have a commercial utility, CCleaner will do).  First - and very importantly - create a backup of the registry. 
 
After the cleanup, I would do an uninstall/reinstall of the drivers using the steps mentioned above.
 
Good luck.