Alright, so I was previously running Windows 7 Home Premium (64-bit) and had a myriad of hardware failures so I bit the bullet and just built a new rig. Everything went just fine, right up until I realized that, duh, the Home Premium edition tops out at 16GB of usable RAM. And of course I'd purchased 32GB of RAM for the new system.
 
So, knowing that I'd need to purchase a full version of Windows to get the most use out of that new RAM, and knowing that I'll eventually have to upgrade to Windows 10 anyway, I did the free upgrade, just to make sure all of my software/hardware worked in the new OS.
 
I'm using a Focusrite Saffire Pro 40 (FireWire) interface, and it didn't work in Windows 10. The Focusrite website stated that the Texas Instruments OHCI IEEE 1394 driver is best suited for the interface, so when I looked in my device manager I saw that it was a VIA driver. I've searched high-and-low for the Texas Instruments driver online and can't find anything. I ran the OHCI Tool as recommended by the Focusrite website, and according to the utility it said my driver was available.  (For the record, my new board didn't have a FireWire port or header, so I'd purchased a PCI-E FireWire card, which I'm using now.)
 
So I bumped back to Windows 7 and now everything works again.
 
The way I see it, my options are as follows:
 
1) Keep my Saffire Pro 40 and somehow find a way to get FireWire to work in Windows 10 so I can eventually upgrade to Pro and take advantage of the full 32GB of RAM I have installed.
 
2) Dump my Saffire Pro 40 and get a USB interface such as the Scarlett 18i20. (Focusrite has confirmed that the new thunderbolt Clarett doesn't work in Windows 10, which is kinda crummy because if one is going to upgrade an interface, thunderbolt seems the way to go!)
 
3) Ditch Focusrite and get another thunderbolt interface that is supported in Windows 10.  (And find a thunderbolt card that's compatible with my board, the ASUS Z170-AR, which only has a thunderbolt header, not a port. The Asus-made thunderbolt card strangely doesn't list the Z170 as being compatible.)
 
4) Forget about upgrading to Windows 10 Pro, stay where I am in Windows 7 Home Premium where everything works as it should, and just bemoan my idiocy for purchasing 32GB of RAM when I can only use 16 of it.
 
I do have Windows 10 running on a secondary computer (no multimedia stuff, strictly an office-type workstation) and while I do prefer the feel of Windows 7, I don't have any serious gripes with it. So I'd prefer to go to Windows 10 Pro, but right now that isn't an option since my DAW isn't much of a DAW without a functional audio interface. :(
 
I'm all ears, folks. If you've run into similar issues or have any insights, I welcome your input.

The only thing I remember seeing when Win10 hit the streets was that Focusrite confirmed that there is an issue with the VIA chipset for the Saffires (no idea of current status though). I am not familiar with Win10, but assume that if it is assigning VIA drivers that the physical chip is also VIA? If so, the best solution is to get a PCIe FW port with a "Focusrite recommended" TI chipset (not a combo port, but a dedicated FW card), and disable the onboard VIA FW.
 
Focusrite has been very upfront about this, and probably has a truckload of data to help you. Honestly, your best solution is to shoot them an email and let them know the new MB and ask them specifically for which FW card to get. They have always be very responsive to emails for me (plus link this thread in the email, so can save you typing... they do read them and sometimes even reply here).

Howdy again!
 
Focusrite does recommend a specific PCIE card with a TI chipset, but they go on to say that it has shown compatibility issues with the Z170 boards, which I now have.

Ouch. My gut reaction would be to stick with Win7 until all is sorted and confirmed, but it is definitely worth the time to ask Focusrite directly. After suffering the "hardware replacement fiasco" going from XP to Win7, I have been very hesitant to experience that again "on purpose." Being unfamiliar with Win10, I would gravitate to "what I know" and save the learning curve for later.

I wonder if there are any versions of Windows 7 Professional still lurking around....that way I can keep my stability AND take advantage of the extra RAM...
 
Hmmm...
 
But yeah, I'm still digging around and will ask Focusrite what they suggest.

streckfus
I wonder if there are any versions of Windows 7 Professional still lurking around....that way I can keep my stability AND take advantage of the extra RAM...
 
Hmmm...
 
But yeah, I'm still digging around and will ask Focusrite what they suggest.

If you decide to go this route, I strongly recommend Win 8.1.  It's the latest (before Win 10), so is much more stable and efficient across the board.  If you don't care for the "Metro" GUI, install Classic Shell (free Win XP/7 GUI emulator).  It takes less than a minute to install, choose the Win 7 default settings and you never have to think about the GUI again! 
 
Also, you don't need the Pro version of Windows 7/8.1, the Standard/Basic edition will make use all of the ram you have just fine. 

Well I was running Windows 7 Home Premium and it was only using 16GB. It stated I had 32GB installed, 16GB available. Maybe Microsoft changed things up for Windows 8.1 & 10 and allowed more usable RAM in the Home editions, but no matter, cuz it's too late now!  Purchased a full version of Windows 10 Pro (64-bit) so I could do a fresh install.
 
I also ended up getting the Scarlett 18i20 because I didn't want to deal with the FireWire hassle with the Saffire. A little bummed to find that the Scarlett doesn't have a "Loopback" feature like the Saffire did...must have something to do with the fact it's USB and not FireWire, but oh well. I didn't use that feature an awful lot.
 
For the record, the main reason I dumped Windows 7 on the new rig was because I was getting frequent lockups, and several software packages failed to install (including SONAR!!) and after reading online a bit, this new hardware I'm running was designed specifically for Windows 10 and a lot of Win7 drivers just don't click. Thus far things have been going great, although I'm only on the Windows Update phase of the install, so time will tell if I run into any problems once it's time to start installing the fun stuff.
 
Fingers crossed.

Hmm.
 
My Motu is connected via a VIA PCIe card - no issues. Although MOTU has a tech note on preferring TI chipsets, it's from 2009.

I know this is too late, but the other way to go would have been to spend approx. $40 for a TI chipset PCIe FW card.  (If I understand your post correctly, you bought a PCIe card, but it was a VIA chipset?).
 

I am running Windows 10 Home premium and using all 32Gig of installed RAM
 
My Focusrite Pro 40 works fine, but then I have PCI TI chip-set card installed.
 
The MoB is ASUS Z97-P 

I doubt TI driver will work with a VIA card different chip sets.

What breed of Z170 board are you using?