Yes.
There's a PCIe card in the TTX3 that the ttx3 multi is setup to utilise to interface with a JVS or a FASTIO IO board. If you don't have this card, then the multi won't work in a cab for you... you'll be limited to playing games with a keyboard only on it. You can effectively use the multi on any computer thats as powerful as or better specs than the TTX3, so long as it has NVIDIA GPU, BUT... without that IO card that comes in the TTX3, you will have no IO interface for your cab, unless you set something else up... but i'm not sure what.
You basically buy the TTX3 for 2 things... 1, because it has a cool etched logo on the cover... and 2... because of that IO card. Yes, you can take the IO card out of the TTX3 and put it in other systems, Someone mentioned last week there was some issues with doing that with JVS, but for FASTIO i can confirm it works well. I've removed it and stuck it in a TTX4, and other pc's and it works fine.
The TTX3 multi works on most computers, including TTX4. The bios password for the TTX4 is on the net, it's not hard to find. You just do the same as with TTX3, access the bios and unlock it and you can use the system, but without that IO card from the TTX3..... you're playing the games with a keyboard and gamepad fo the games that are setup that way. TTX3 is plug and play, just get your JVS or FASTIO board and shove it in your cab.