Refresh Rate Handling - 23.976 Hz Works!

Readers following our HTPC reviews know by now that Intel's 23 Hz issue was left unresolved in Ivy Bridge. It is definitely better than the Clarkdale days, as users no longer get 24 Hz when setting the display refresh rate to 23 Hz (23.976 Hz intended). However, the accuracy is not enough to prevent a frame drop every 4 minutes or so (the 23 Hz setting results in a display refresh rate of 23.972 Hz in Ivy Bridge). One of the first things I checked after building the Haswell HTPC was the 23 Hz setting. The good news is that the display refresh rate accuracy is excellent.

Even better news is that the set of display refresh rates obtained with the Haswell system is more accurate than anything I had obtained before with AMD or NVIDIA cards. The gallery below presents some of the other refresh rates that we tested out. madVR reports frame drops / repeats only once every 6 hours or more in the quiescent state.

Unfortunately, Intel still doesn't provide a way to easily configure custom resolutions (in fact, the latest driver release seems to have removed that option completely. Update: A reader pointed out that the feature is still available as CustomModeApp.exe in the drivers folder, but long time users still miss access to it from the main control panel). I know for a fact that my Sony display (KDL46EX720) does support 25 Hz and 50 Hz refresh rates, but Intel doesn't allow those to be configured. We are willing to cut Intel some slack this time around because they have finally resolved a bug that was reported way back in 2008.

Video Post Processing and HTPC Configuration Options Decoding and Rendering Benchmarks
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  • Surlias - Friday, December 06, 2013 - link

    Hey, I just bought my first 120 Hz capable HDTV, and I'm wondering how to configure it for both gaming and proper 24p media playback. Can I set the a custom resolution of 1920x1080 @ 120 Hz (GTX 770) just like you can with a 120 Hz monitor, and then leave it at that setting all the time? Then games would be able to do VSync up to 120 fps, and media would be able to lock in at 24p because it's an even divisor of 120. Or is this not possible on a TV due to HDMI limitations? If this is the case, then will it be necessary to manually switch back and forth between 60Hz and a 24 Hz custom resolution depending on the usage situation (since 24 Hz would be awful for gaming)? I've always found this particular subject confusing and I'm hoping someone can help me understand how this works. FYI, I mostly use XBMC for media playback, which has an option to "sync to display refresh rate", which I assume would be essential for enabling 24p playback. Reply
  • redmist77 - Tuesday, April 08, 2014 - link

    I'm amazed at how well Haswell locks the video and audio sync. I can output 23.976Hz video to my plasma TV and all of the AV sync graphs in MediaPortal or MPC-HC are *dead* flat and there's never a stutter. 24Hz, 50Hz and 59.94Hz are all perfect too. That's possibly the holy grail of a HTPC. I haven't found any other bugs (DXVA2 etc.) either so it's looking good. DTS-HD, Dolby True HD bit streaming also works perfectly. 0-255 RGB HDMI output requires a registry fix but that's no big deal (default is 16-235)

    The next great challenge is a gaming HTPC that uses Intel 4600 for video and a giant PCI-E card when launching a game ;) I've sort of got it working using DisplaySwitch.exe and two HDMI inputs on my AV receiver but it's not quite seamless.
    Reply

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