TV just refusing to accept DVI-HDMI PC input

I'm enjoying FFXIV:ARR PC a lot, so much so that I'd like to play it on my bigger TV. Problem is, it's just not displaying my computer period.

This is strange because:
1 - It has worked in the past using the exact same hardware setup. AFAIK, drivers never changed either.
2 - I know the PC and cable work well, because I can connect it to an old projector and it'll display it fine.
3 - I know the TV's HDMI port works because it displays PS3 stuff just fine using the exact same port.
4 - I know it's a compatible resolution/hertz for the TV, as I'm using the same one that worked before (had it saved in an UltraMon profile).
5 - Since I can get the old projector to work with the cable, I know it's not a multi-display new driver issue or anything.

So the PC and cable are fine, the TV and TV's HDMI port is fine, but they suddenly refuse to work together when they worked just fine in the past.

What the heck could cause this? It's frustrating the hell out of me.

EDIT: I forgot to note that the computer with the non-displaying TV is acting just like it does with the working projector. It shows it, it says it's working fine, has no problems, etc. Lets me adjust all setting and the like. It just isn't actually displaying. The TV is not giving any alerts like "too high resolution", "improper frequency" or the like, it's just flat out blank, like there is no signal at all.

 

Tried it with TV on first and with it off first, neither worked.
I'm not sure I understand what else you're asking. On the Nvidia Control Panel and the UltraMon interface, it says "LCD TV" when the non-working TV plugged in, and "Mstar Demo" when the working projector is plugged in. If you're asking if my PC lists the non-working TV, then yes.

No, Magnavox.

 

There's nothing wrong with the ports on the TV, as I said I use the exact same port with my PS3, and it's working flawlessly. I'm even watching 1080i Pawn Stars on DISH TV via HDMI (fake and scripted as hell, I know, it's mostly for background noise) right now on the TV, no issues whatsoever. It's just my computer that refuses to display on it. Yet my computer can't be at fault either, because it'll do it's secondary display on the old projector without any issues...... It's confusing the hell out of me.

 

I forgot to note that the computer with the non-displaying TV is acting just like it does with the working projector. It shows it, it says it's working fine, has no problems, etc. Lets me adjust all setting and the like. It just isn't actually displaying. The TV is not giving any alerts like "too high resolution", "improper frequency" or the like, it's just flat out blank, like there is no signal at all.

 

Extended, Clone, Single Display, etc, all fail.
It's a black screen with "HDMI 1" at the top, meaning it's not detecting a signal at all.

 

No workie. Exact same problem.

 

I just gave up on trying to get HDMI to work again, it's even stumping everyone here.
I managed to find the component RGB adaptor for my video card, and what do you know, it works fine with the same TV that's refusing HDMI PC input. It's only 1080i, sure, but at least it works.

Thanks everyone for trying to help me, but I found an alternate solution