I'm looking at making my HTPC 3d-able. I'll be picking up a 3d display at some point in the future and the only option for pcs at the moment is to go with the nvidia offering. At present I've got a HD 5750 in my HTPC, it's mostly for watching films but I do play the odd game (Left 4 Dead 2, etc) which it's fine for.
The case is an matx so I have to stick with small power supplies, as such I've managed to get a half decent (but not fantastic) 500w power supply and that's honestly about the best available for my size case.
So i'll be getting rid of the HD 5750 and going for something from nVidia instead, I want something of roughly equal performance and something that doesn't draw too much power.
For games you'll want to check out either Tridef DDD or iZ3D, which work with both nVidia and AMD cards. I'm personally using iZ3D on a GeForce 9800GT outputting to a Samsung PN50C7000 Plasma and have found the 3D effects to be fairly impressive in several games. Having zombies run out at you from a 50 inch TV is pretty awesome in Left4Dead2. The interior shots in Starcraft 2 are also very cool in 3D, however, it's little cumbersome when you actually get into the RTS mode and try to play in 3D.
I was able to successfully output to 3D using an AMD Radeon 5450 on the HTPC, but I had to swap it out for the 9800gt due to poor framerates. The main problem I found with the iZ3D drivers were that I had to set all the games to output at 1920*1080 to have the stereoscopic 3D effect work properly using the top-bottom 3D mode. I'm still looking to find a way to play games in 720p because I want to go back to the fanless GPU. The one bonus the iZ3D drivers have over the Tridef DDD drivers is that they currently support DirectX 10 and 11.
I haven't actually tried watching any 3D blurays yet because I don't have a bluray drive, but it seems like there are a couple media players that allow 3D playback from an HTPC. I think you'll need to purchase either Power DVD 10 Mark II or Arcsoft Total Media Player 3 with the Sim3D plugin.
One of the best blogs I've found for anything 3D is http://3dvision-blog.com/
If you still want to change out your GPU to an Nvidia card then you'll need to have at least a GeForce 9600GT to run Nvidia's 3D Vision. The 9800gt I used to replace the Radeon 5450 is a low power version that doesn't even have a connector for the additional 6 pin power pin. This means that it can't draw more than 75 watts due to the power limitation of the PCI-e slot. I'm not sure if they actually sell that model outside of Korea but the model was MSI Geforce 9800GT N9800-md512 vf1050
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