tricky fullscreen overscan issue

I swear I'm about ready to give up on this one, hopefully one of you crazy tech-heads will know whats going on.

Video Card-Nvidia GeForce 8400GS, with latest drivers
TV-Panasonic Plasma, TH42PX60U
OS-Windows 7 Ultimate, 64Bit
TV and card connected with a DVI-HDMI cable
Native Res-1024x768
Custom Res for overscan compensation-1862x1048

Anyways,

While in Windows I'm getting overscan, I can fix this by going through Nvida's software and resizing my desktop/setting a custom resolution. Everything looks great, my movies play, desktop looks good, no edges missing, it's perfect. The problem I have is I like to play some really old school games and most of them require low resolutions. When started they go to fullscreen and my overscan comes right back. This doesn't happen with all my apps, mainly on older/less supported ones.

I can sometimes fix this with an .ini edit but that isn't always an option. I've tried using powerstrip to assign a custom res to the app that isn't working with no luck. Also this plasma doesn't have any options regarding overscan or true 1:1 pixel mapping, so no help there. As a last resort I could go into my plasmas service menu and adjust but I really don't want to deal with that.

I'm willing to buy a new graphics card but I need to know why this is happening first. I know DVI is mainly used for PCs and HDMI for TVs so I'm guessing this might be a problem. Is it my DVI-HDMI connection? Would using a straight HDMI-HDMI cable fix this? I was thinking that maybe there might be an application launcher for older apps that lets you force a resolution but I don't know of any and since powerstrip did nothing for me I'm not holding out much hope.

Can someone tell me why this is happening?

Yeah 1024x768 is the native res for the tv so I tried that first with about %5 overscan. The card doesn't have a component output but I did try an S-Video cable which worked perfectly, this is kinda why I thought it might be the DVI-HDMI cable causing it.


Unfortunately the tv doesn't have any setting for overscan or 1:1.

It just really weird it's like the game doesn't even look to see what my Windows res is set at and resets my tv to it's native res (bringing back the overscan). Thanks for the replies I'm going to search around for a new graphics card and just pray it doesn't suck.

Either that or use peanut butter =D
http://www.youtube.com/watch?v=_p52QJi-Ydo