Weird audio / video PC problem

Okay so here's what's going on. I have a media center / gaming PC that I've been using for years. I send the audio and video from it to a Samsung 8500 series TV via hdmi, then the audio from the tvs optical out to a surround receiver. Well after the last video card upgrade the strangest thing happens. Any av source will play for a bit, a random amount of time, then the video drops to like 1/3 speed and the audio cuts out.

The computer is fine otherwise it's not like system-wide lag. Just the video in the window or app. whether a local file, streaming from an app, or YouTube videos, all encounter this within a minute or two after beginning to play. Even stranger, I can use the optical output from the Mobo no problem. If I go to the sound default device and change it to the Mobo the video jumps back to normal and audio plays from the optical out on the computer flawlessly. Change it back to hdmi and it works as long as you don't trigger any system sounds like the click sound of opening a folder or an email notification. If you do, it immediately drops your sound and video goes back to 1/3 speed.

clues that might help..
It really is exactly 1/3 speed, I've timed the seconds ticking off in the video vs. on my watch and it's 3 ticks per second of video.

Looking at the audio meter in windows while it's happening shows the meters moving like it's still outputting, but they're also at 1/3 so they go up n down just slowly. And there is no sound from the TV.

Like I said before, if you start a video, switch audio output devices, then switch back to hdmi, audio works for an extended period, but, any disturbance of the computer, even just autoplay loading the next video, or any system sound, triggers the glitch.

Intel Core i7 980 extreme.

16 gigabytes of DDR3, in an Asus Sabertooth x58 mobo.

on board Realtek alc892 8 channel surround audio.

nVidia gtx950 (4gb ddr5) in a pcie (2.0 X16) slot solo.

other Mobo slots are filled as well except the other x16 slot that would pair up for sli. I left that one open. It has a Bluetooth /wifi card, and a Hauppauge TV tuner card.

Drives are, C: Samsung 950 256gb ssd primary and a pair of crucial 1tb ssd's in raid as my D: (recording drive)

What I've already tried so you don't have to ask...

uninstalled the hardware and deleted all drivers for the video card and sound device. Then Downloaded the latest drivers from Nvidia and Realtek and reinstalled them. Fail.

Changed the output bit rates on the sound card through all the different bps options. Fail.

Tried a different TV. Fail.

Completely formatted the c drive and reinstalled Win7 ultimate. Then installed the video & sound using the downloadable whql drivers from windows update. Fail.

Used the original sound card driver from the Mobo's oem cd. Fail.

Update the Mobo to the latest bios. Fail.

Disable onboard audio all together from the bios. Fail.

Moved the other cards in the pci-e slots to different slots. Fail.

Removed all other pci-e cards completely so it was just the video card by itself on the pci bus. Fail.

I'm out of ideas. The computer doesn't report any errors or misbehave otherwise. It seems like some some sort of hardware level glitch between the on board audio and the video cards audio device. Any help appreciated


Posts: 1,125   +189
Try checking the HDMI cable first and get it replaced with a newer brand.
You're going to hate this idea and me with it, but try reinstalling windows from scratch.
Back up any files first then do a clean install, if it still screws up even with the most up to date drivers.
Consider buying a new mobo, ram, cpu, I know you don't want to hear that but things happen. =/
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