nVidia HDTV Stuttering Resolved.. Maybe

[Humanzee]

First off I will appologise for repeating some of this from other threads but I thought it was worth its own.

So I have been having problems with my 6600GT and HDTV since I got this setup. Lots of stuttering, dropped frames and pixelation, inconsistency between video playback applications. Some posts in the forum suggested some settings that improved playback to a degree but didn't make it great. I had basically given up on it and resolved to build a new machine some day with PCIe a faster processor and at least a 7600 series graphics card.

So, this evening we were trying to watch Letterman in HD over dinner and it was particularly awful. (the stuttering that is) The wife said, is that in the recording? I said "hmm lets find out", so I switched to a windowed view and the stuttering went away. I said "looks like we need a better computer." She said something that I won't repeat. Anyway, I was suddenly inspired to try again at figureing this problem out.

So to this point I thought I had tried everything.

*updated all my graphics and chipset drivers and installed the latest purevideo decoder.

*I reduced my resolution from 1080p to 720p

*I switched to Overlay from VMR9 FSE as my Video Renderer

*I made sure that PureVideo was my prefered decoder in DECCHECK and set sage to use "Default" as the mpeg2 video decoder filter.

*I double checked that the purevideo tray icon showed up when playing an mpeg.

*I enabled hardware acceleration in the PureVideo Settings

*I set "Automatic" as the de-interlace mode.

*Overclocked my GPU with the "coolbits" registry setting

*Overclocked my CPU

None of this really helped. But then recently I read a story online about the upcomeing HD purevideo technology and how it requres a faster graphics core frequency vs. a fast 3d rendering capability, All this time I have been overclocking my 6600 GT I have been focusing on the 3D performance overclock. So I thought I'd go in there and tinker with the core frequency manually and see if I could manage some improvement. I have always run the "Detect optimal frequencies" feature and not pushed the limits but I figured it was worth it vs buying new hardware.

Originally Posted by AnandTech article

As PureVideo HD performance is dependant on the GPU's core clock speed, the impact of PureVideo will vary depending on the speed rather than the 3D power of your graphics card. For example, our MSI 7600 GT HDCP runs at a default 580 MHz core speed. This makes it a more effective PureVideo card than a 7900 GT running between 450 and 500 MHz. NVIDIA allowed us to underclock the MSI graphics card and test a variety of settings between 350 MHz and 580 MHz in order to fully understand the way performance varies versus GPU clock speed.http://www.anandtech.com/video/showdoc.aspx?i=2798

With the "cool bits" registry hack, there are two different "settings" to overclock, 3D and 2D. You can adjust both the core frequency and the memory frequency for both. I upped the 3D core freqency from 553 which the software had detected as optimal to 570ghz ran the test and it passed. I had never even clicked on the 2D settings before, but what I found was that the core frequency for 2D was only 300Mghz. Vs. the core in 3D running at 570mghz. So I said what the hell and jacked it up to 570 just like the 3D settings. I ran the test and it failed, but it did stick at 500mghz. So I applied the settings and loaded sage again. (see attached pic)

At 720p in overlay everything is golden. I watched about 3 hours of HD recordings and they have never looked better. Now, I can't guarantee that I won't end up cooking my 6600gt but things look good for now. Here's crossing my fingers. I tried VMR9 just for grins but it locked up sage tight. Oh well. I havn't tried this all at 1080P yet but it certainly works at 720p. I guess maybe much of the conflicting reports about the success of the different nVidia cards could boil down to differences in the default core speeds of different cards from different vendors.

So, if you are having problems with your nVidia card and you are brave, find out about the cool bits registry edit and give a shot at increasing your core speed. It seems to have done the trick for me. I think I just bought this computer several more months of abuse before I turn it into a client.

As always your mileage may vary. Have fun