Windows 7: Graphics card to HDTV issues

My problem:
Ati Radeon 5670 (had for about 3 years no problems until now)
Samsung 2333HD 1920x1080 (had for about 3 years no problems until now)
My 5670 has always displayed via HDMI (HDMI cables are not a factor in this issue, as I have tested it with 5 different cables) onto my 2333HD (at 1920 x 1080), however, without me changing or touching anything, yesterday I turn on my PC and the TV says "no signal", as apposed to "check signal cable", which indicates no connection. So the TV recognises that something is plugged into the HDMI slot, but that's it. Heres the strange part, two different cards (both Nvidia, not that I imagine that has much to do with this) work fine, displaying correctly through my TV AND when my PC is plugged into a different HD display, my graphics card works fine.
summary:
MY graphics card -> MY TV = doesn't work
DIFFERENT graphics card -> MY TV = does work
MY graphics card -> DIFFERENT TV does work

I have tried restoring the ATI catalyst settings to default, changing my graphics card to 720 on a different display then plugging it into mine, and I have tried 800x600...
I would really like to have this fixed and working how it used to, and even after a day this is causing me stress >:/ My graphics card has a DisplayPort output so I was thinking if theres no success, I could try using a DisplayPort to HDMI cable, would that work?

I greatly appreciate any help, I am able to troubleshoot most hours and I will try and reply as fast as possible to any contributors.

Can anyone tell me if it is either the Tv or the card at fault? Also, help would be greatly apppreciated.

Only trial-and-error, and swapping both components, would point the finger at the proper culprit.

Since you probably don't have another video card to try (unless you have a second machine that also has a video card with HDMI output) do you have another HDTV in the house you could try connecting to this HD5670 card instead of the Samsung?

From what I've found, the Samsung also has a DVI cable connection. Have you tried connecting the HD5670 to the Samsung via DVI instead of HDMI? (it will look much better, as I can attest from my own setup with an HD5770 that connects to a dual-mode Eizo HD2441W either through DVI at 1920x1200 at 60hz, or via HDMI at 1920x1080 at 50hz and slightly overall reduced in screen real estate used).

Since the Samsung has a DVI connection as does the HD5670, is there a reason you went with the HDMI path from the HD5670?

thankyou so much dsperber I will go get searching for a dvi cable right away. I guess i originally went with HDMI because it was what I was used to with my blu ray player, hd digital box and xbox, it wasn't for lack of a socket, just got to figure out how to get the sound from my computer to my monitor, or will i need to buy some speakers? I really appreciate your contribution and you may have just saved me from getting a new card

Well, the speakers in your monitor are probably not terrific, and they're 2-channel only anyway.

So invest in some powered external speakers (quality and price is up to you, can be 2.0, or 2.1, or even multi-channel if your PC's sound card supports HD Audio), and plug it into the lime-green "speaker" connector (most likely) on your motherboard or sound card. This will give you 2-channel stereo sound. Multi-channel sound output uses multiple output connectors on your motherboard, if you want to go that route.

But I'd certainly not remain intent on using the TV's speakers. I'd go with DVI from HD5670 to the Samsung (for BEST video), and then external speakers connected to your motherboard/soundcard for sound.

Yeah, I've already ordered some descent speakers for a good price, thery're mainly so I can have quick and easy volume control for my high quality headphones, with their function as actual speakers being slightly less important. The new cable should arrive on saturday, but it could be friday or monday, I'll post the results up here as soon as I get them. Thanks for the help dspsrber, I really appreciate it.

Just adding my 2 Pence here:

When I first got my 24" Iiyama monitor, I connected via HDMI and had problems. No sound to (2:1 + Woofer speakers) Quick consultation with IT and Network Engineer grandson, removed HDMI, installed DVI - problem solved.
Working fine on WMP from tuner card connected to my ATI Radeon 6770. I know you are connected to a TV, but same principle if monitor is HDCP.

Thanks Bertison, hopefully I'll my DVI cable by saturday..

thanks guys the DVI cable works perfectly

Excellent!

Actually, I would guess it possibly works "better than perfectly" in that I suspect your desktop resolution with DVI would absolutely increase up to the maximum (i.e. "recommended") resolution of your monitor. If you'd been using HDMI previously, and if you monitor can actually display at higher than 1920x1080, then all you were getting with HDMI was less than you could have been getting with DVI.

For example, as I mentioned earlier, I much prefer DVI with lets me have full 1920x1200 on 100% of my Eizo HD2441W (for its "look" as well, not only for its desktop resolution). In contrast, using the monitor as a Windows desktop through HDMI forced it to 1920x1080 and used maybe 96% of the Eizo screen width, which has to be something about the monitor's full-screen HDMI mode via HD5770 - > HDMI to AVR -> HDMI to Eizo I guess. In contrast, feeding it "external native HDMI at 1920x1080" (say from a BluRay player or DVHS VCR) uses 100% of the Eizo width.

Anyway, I'm sure you'll be happy with your new DVI connection method.