home theater 5.1 optical to pc, cant get true 5.1?

Try right clicking your volume control > playback tab > right click "Speakers" > configure speakers. I have an Asus M5A99X, one step down from yours, although I think this is a Windows choice, and I have the choice of: Stereo, Quadraphonic, 5.1 Surround, and 7.1 Surround. If you look 2 icons to the left of the normal volume control there is a RED volume control icon to bring you to the "Realtec" sound setup which is much more elaborate in choices, including DTS and DSP sound effects and many options under Optical output. If your MB doesn't use the same Realtec chip as mine, yours could be different!

I think you have to set the soundcard so that it outputs a compressed format, such as Dolby Digital or DTS. Optical cable can only handle two channels of uncompressed PCM.

http/en.wikipedia.org/wiki/TOSLINK

Best thing to do if your AV Receiver has HDMI input is to run a HDMI cable from your graphics card, you can get full uncompressed 192khz 7.1 that way to your receiver.

I don't mean to be rude, but you are incorrect. If you read your link more carefully, they are saying that the standard DD and DTS are not compressed and work fine on the optical SPDIF. It is the newer 24 bit DD Plus and DTS HD that have too much bandwidth for this older format to handle. Newer optical formats and HDMI can easily handle this high data flow, it is simply that the Toslink SPDIF standard was developed in the early 80' when CD's first came out and was only intended ( at the time ) to carry two channels of 16 bit/ 44Khz data.

I guess i just didn't phrase it well enough.
What i meant was, if you want to output uncompressed PCM (which i assume is Windows' default, but i've never checked), you're limited to two channels.
But when using Dolby Digital or DTS (which are both compressed, lossy formats), you can have up to 7.1 channels.

When i was skimming over the article i didn't notice your point about the newer formats (TrueHD and MasterAudio). Since these aren't supported, I think i agree with mauller07 when he says to use HDMI, instead.

My apologies to Andrew_berge, I worked in the AV industry for 27 years and assumed I knew everything....foot in mouth! The original DD AC3 tracks were compressed and lossy. I wrongly assumed that the original DD track was uncompressed, and it was the newer higher bandwidth tracks that forced Dolby to start compressing the tracks. I went back to the source, Dolby Laboratories, as sometimes Wikipedia is wrong, and found that even the oldest AC-3 codec used lossy compression. I assumed that the codec simply mixed the 5.1 channels into one bitstream, but compression was not used. I hate being wrong, I'll go eat some worms!

No need to apologize to me. We both learned something

you need to make sure to set your sound output in windows to the HDMI output on your graphics card.

your samsung 5.1, is it a HTIB (home theater in a box) type unit? ive heard of issues with some of these where they are not providing surround sound via auxilliary (ie, anything but the included dvd player) inputs and only provide stereo. look in your manual to see if there are any such limitations listed. it could very well be the PCM issue with optical listed above but i think hdmi inputs were tried as well if i remember.

i personally have my receiver (not from a htib set) connected up to my pc via a dvi-to-hdmi cable and i get perfect 5.1 sound. from the pc it is either stereo (while in windows), DD (while playing movies) or i believe PCM (while playing games). I have a ps3 hooked up and it plays via PCM on a hdmi input as well.

you can see the receiver, pc, ps3 and some speakers here...


this is the type of cable i use...


in my windows settings my receiver (in this case vsx-30) is displayed as the primary audio device.

this is what the windows 7 sound devices looks like...


a direct hdmi cable (instead of dvi-to-hdmi like i did because my gtx470 doesnt have hdmi) should work similarly.

i know spdif will support 5.1 speakers (after all the logitech z5500 5.1 uses spdif in) but as mentioned earlier this might be for normal DD and not newer formats. i also know that people can and do use spdif optical to get 5.1 sound out of receivers.

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try hdmi input but it sounds like it may be an issue with your receiver if you have a htib set.

also make sure that you are playing a 5.1 audio source such as a dvd or game. windows will be stereo only!

let us know the results.