Realtek ALC889 vs. ALC892

[ronch]

Hi Gerbils. Last month I got myself an MSI 990FXA-GD65 (GD65 for short) to replace my MSI 785GM-E65 (and E65 for short). The GD65 sports a Realtek ALC892 audio codec, which seems to be overwhelmingly popular these days with the newest boards. Looking at their respective pages on Realtek's website, however, I noticed that the ALC889 actually has better SNR than the ALC892, which is several dB lower. The ALC892 supports THX. Whether or not that offsets the lower SNR, I'm not sure.

http://www.realtek.com.tw/products/prod ... ProdID=173

http://www.realtek.com.tw/products/prod ... ProdID=284

Also, with the E65, I can plug my 2.1 speakers into just about any jack because the ALC889 supports jack retasking. The ALC892 supposedly also has this feature but I've noticed that with the bundled drivers, I can only plug my speakers into the default jack (top-middle). I downloaded Realtek's driver (2.70), which improved the situation by allowing me to plug my speakers into the top three jacks but not the bottom three. Unfortunately, I noticed that Skyrim is having trouble with a missing DLL file with the drivers I downloaded (missing X3DAudio1_7.dll). Not sure if it's caused by DirectX or Realtek's drivers or CCleaner removing important files, but I'm inclined to think the drivers I downloaded from Realtek may be missing this file. Unfortunately, the drivers that came with my board are a bit lacking in terms of jack detection. Any thoughts?

[just brew it!]

In practice, you're probably not going to notice the difference between DACs with 95dB and 108dB S/N ratio for onboard audio. That's the raw S/N ratio of the DACs in the codec chip, and says nothing about how well the motherboard maker integrated the codec into their design. Unless they've taken great pains to shield the audio section from EMI and provide extra filtering (dedicated voltage regulator) for the power to the codec, I seriously doubt you're going to get to 108dB S/N. Even 95dB is probably a stretch.

Where did you see that the 892 is THX certified? It's not on that page you linked. THX certification isn't particularly meaningful anyway; it's not a capability per se, all it means is that a piece of equipment meets certain minimal standards for fidelity.

Edit: Also note that the inherent best-case S/N of a 16-bit digital audio source is 96dB. So 108dB is overkill anyway unless you're listening to a lot of material with 24-bit audio tracks...

Edit 2: A bit of speculation on my part - Realtek probably figured out that hardly anybody was actually taking advantage of the 108dB S/N capability, and decided to produce a cost-reduced version of the 889. These codecs appear to be essentially identical other than the S/N quoted in the specs; and a drop in S/N from 108dB to 95dB is consistent with them switching from 18-bit DACs to 16-bit DACs. Making an accurate 18-bit DAC is tricky because of the tight tolerances involved. It's conceivable that the 892 could be an 889 with the 2 least significant bits of the DACs disabled (or maybe the 892s are just 889s that didn't quite pass QA tests to verify full accuracy of the DACs, similar to how CPUs get binned based on clock speed headroom).