Leave it to Avid to change system requirements in a point release.
Is there a solution?
tl;dr no there is not
Don’t believe me? Let’s go down the rabbit hole…
The Issue
Older systems whose CPUs do not support the SSE 4.1 instruction set will not be able to install or run MC 8.3. As well it appears that the 8.3 updater.avd writes an expiration date to your dongle (if using one).
Anyone still rocking an HP xw8400, your bus stops here.
Hardware Compatibility
The HP xw8400 technical documents state official CPU compatibility with only 5100 (woodcrest) and 5300 (clovertown) Xeon processors. None of them support SSE 4.1, so that’s a dead-end.
The earliest SSE 4.1 support arrived with Penryn, and although theoretically the xw8400 might be able to run the FSB1333 XEON 5200/5400 processors, HP never provided support for them in the BIOS and their last BIOS revision (02.38 Rev.A) was in 2010.
I’d say that’s a dead-end.
Modders to the Rescue?
Thankfully there is an active community online who modify BIOSes. Sadly it seems HP is a tough nut to crack as they are often encrypted. Here’s a few tutorials on modifying BIOSes for the brave, though it seems like you have to find an alternate OEM BIOS as a starting point, and that seems unlikely.
If that’s not a dead-end, it’s awfully close.
Emulating SSE 4.1 calls
That leaves emulating SSE 4.1, which was shown to be possible by resourceful coders working on the Oculus Rift.
Luckily enough Intel produced an emulator themselves, and it seems to have been met with some success, at least within the confines of operating an Oculus Rift.
A dead end? Probably. I gave it a try and no dice; the installer still bails at the same point. Avid might be doing a processor-class check as opposed to simply trying to make a SSE 4.1 call, and I suspect there’s nothing the emulator can do about it.
I’d say that’s the end of the road. In a theoretical sense I suppose you could install Avid on a qualified system, transfer that install back to an xw8400 and then invoke MC with the emulator but I’m not about to try it.
Just gather up some pocket change and hit eBay for an xw8600. Those should work with 8.3.