Help Building 5.1 surround HTPC

I've built many PC's, low and high end. However I've never built an HTPC and I'm considering building one for my Den. I already have a fairly new but inexpensive 5.1 surround sound receiver. It has digital audio optical in, digital audio coax in, or 6 RCA jacks for analog audio in. It does not have an HDMI in or out. I also have a mid-range quality five speaker set with a powered subwoofer. This sound system is currently connected to my HDTV via the digital audio coax out from the TV. All my devices, (Xbox 360, standard DVD player, Dish DVR, etc...) are connected to the TV via HDMI cables. In this way I can just change the input on the TV to the desired device and then the TV outputs the digital audio signal to the reciever/amplifier connected to my 5.1 speaker system. I'm not really interested in changing my audio system, I just want to build an HTPC that will output 5.1 surround sound to my existing audio system.

I already have a fairly new LG Blu-ray drive to put in the HTPC along with some other components, but I will be buying the CPU, mother board, memory, sound card, and video card new. I also have the full version of PowerDVD 10 which I understand plays Blu-ray and 5.1 surround. My question is, what is the best way to go about this? As I consider this build, I know that the video card I buy will have an HDMI out for the video, but as far as I know the audio will have to come separately from a sound card. Correct me if I'm wrong, but I'm fairly sure modern PC's transfer the audio signal generated by the optical drive over the PCI bus. Does the optical drive send all the channels for 5.1 surround to the sound card in a single data stream over the PCI bus and then the sound card decodes it? This is where I'm not sure I understand what is happening to the audio in the PC, which components would be best for my existing equipment, and how to set it up correctly. I understand that with my low end receiver/amplifier I may have to give up some sound quality. That's OK as long as I get true 5.1 surround with positional audio and subwoofer effects. Any information and advice is greatly appreciated.
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  1. if you are going to be using a receiver then you do not need to buy a soundcard. i am not sure about a direct video card hdmi output but i know for a fact that if a soundcard supports sound out via dvi (most new cards do it seems) then using a propper dvi-to-hdmi cable will output both sound and video along the cable to the device at the other end.

    for me i have my pc connected to the receiver with video passthrough to the tv. since you said your tv filters out the sound and passes it along to the receiver you can probably hook it up like your other devices are.

    if you are out of hdmi ports you could always use a hdmi switch.
  2. It sounds like you are saying that HDMI signal output from the video card will have the sound encoded along with the video? Please confirm that I'm understanding you correctly. I knew that DVD players, DVR's, and video game consoles did that, but I didn't imagine that a PC with a separate Blu-ray drive and video card connected via a motherboard would do the same. It does make sense though if I'm understanding correctly that the video card HDMI signal will automatically have the audio bundled with the video. In that case you are right, I wouldn't even need a sound card. I could just output the HDMI to the TV and the TV would then send the audio only to the receiver as it is doing for the other devices. I'm curious though, what do you mean when you say that you have your PC connected to your TV with video pass through? Thanks for your help.
  3. Best answer
    i will repeat this again just so we are clear: i am not sure about video cards with hdmi output as i only know about what i use: dvi output with a dvi to hdmi cable.

    with that said...

    yes, my video card transmits both audio and video through this cable. by video-passthrough what i meant is that the hdmi cable from my pc connects to the input on my receiver. the output on the receiver is connected to my television. i do not have the receiver doing any post-processing effects on this feed so it is essentially "passing through" the receiver directly to the television. the sound signal is split away and processed by the receiver before being sent to the speakers.

    my motherboard does have integrated sound but it is my opinion that all of the processing is done by the receiver. the receiver will end up being your primary audio device under settings and doesnt have any audio settings in windows for you to tweak. you will control sound modes through your receiver.


    remember that your situation is a bit different than mine.

    you are connecting to the tv first and running a spdif back to the receiver.

    if your television can seperate the signal and run the full surround back to the receiver via spdif or hdmi then it probably will work but thats all i can say as i've never attempted what you have planned.
  4. I won't hold you responsible if it doesn't work and I greatly appreciate your input. I suspect that it will work because there is no question that I am getting positional surround sound from my Dish DVR and Xbox 360 with this setup. The TV is definitely outputing 5 channels to my receiver from the devices currently connected to the TV by HDMI cable only. Worst case scenario is that audio does not get sent to the TV with the PC connected via HDMI cable only from the video card. I was going to build an HTPC with a nice video card anyway so nothing lost. I will just at that point have to do more research on how to get 5.1 audio from the Blu-ray drive to the receiver. Thanks...
  5. Best answer selected by jimwalker.
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