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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  • HisDivineOrder - Tuesday, June 04, 2013 - link

    I've heard this song and dance before. It never happens. Plus, limiting people to GDDR5 of pre-determined amounts for a HTPC seems like an exercise in being stupid. Reply
  • Spunjji - Tuesday, June 04, 2013 - link

    Yeah, I'm not buying that rumour. Doesn't make much sense. Reply
  • JDG1980 - Sunday, June 02, 2013 - link

    It's good to see that Intel finally got around to fixing the 23.976 fps bug, which was the biggest show-stopper for using their integrated graphics in a HTPC.

    Regarding MadVR, I'd be interested to see more benchmarks. How good can you run the settings before hitting a wall with GPU utilization? How about on the GT3e - if this ever shows up in an all-in-one Mini-ITX board or NUC, it might be a great choice for HTPCs. Can it handle the good scaling algorithms?

    My own experience is that anti-ringing doesn't add that much GPU load. I recently upgraded to a Radeon HD 7750, and it can handle anti-ringing filters on both luma and chroma with no problem. Chroma upscaling works fine with 3-tap Jinc, and luma also can do this with SD content (even interlaced), but for the most demanding test clip I have (1440x1080 interlaced 60 fields per second) I have to downgrade luma scaling to either Lanczos 3-tap or SoftCubic 80 to avoid dropping frames. (The output destination is a 1080p TV.) I suspect a 7790 or 7850 could handle 3-tap Jinc for both chroma and luma at all resolutions and frame rates up to full HD.

    By the way, I found a weird problem with madVR - when I ran GPU-Z in the background to monitor load, all interlaced content dropped frames. Didn't matter what settings I used. Closing GPU-Z ended the problem. I was still able to monitor GPU load with Microsoft's "Process Explorer" application and this did not cause any problems.

    Regarding 4K output, did you test whether DisplayPort 60 Hz 4K works properly? This might be of interest to some users, especially if the upcoming Asus 4K monitor is released at a reasonable price point. I know people have had to use some odd tricks to get the Sharp 4K monitor to do native resolution at 60 Hz with existing cards.
    Reply
  • ganeshts - Monday, June 03, 2013 - link

    This is very interesting.. What version of GPU-Z were you using? I will check whether my Jinc / anti-ringing dropped frames were due to GPU-Z running in the background. I did do the initial setup when GPU-Z wasn't active, but obviously the benchmark runs were run with GPU-Z active in the background. Did you see any difference in GPU load between GPU-Z and Process Explorer when playing interlaced content with dropped frames? Reply
  • JDG1980 - Monday, June 03, 2013 - link

    I was using the latest version (0.7.1) of GPU-Z. The strange part is that the GPU load calculation was correct - it was just dropping frames for no reason, it wasn't showing the GPU as being maxed out. For the video card, I was using the newest stable Catalyst driver (13.4, I believe) from AMD's website. The OS is Windows 7 Ultimate (64-bit).

    The only reason I suspected GPU-Z is because after searching a bunch of forums to try to find out why interlaced content (even SD with low madVR settings) wouldn't play properly, I found one other user who said he had to turn off GPU-Z. I cannot say if this is a widespread issue and it's possible it may be limited to certain system configurations or certain GPUs. Still worth trying, though. Thanks for the follow-up!
    Reply
  • tential - Sunday, June 02, 2013 - link

    I don't understand the H.264 Transcoding Performance chart at all can someone help?

    QuickSync does more FPS at 720p than 1080p. This makes sense.

    The x264 on the Core i3 and core i7 post higher FPS in 1080p but lower in 720p. Why is this?
    Reply
  • ganeshts - Monday, June 03, 2013 - link

    Maybe the downscaling of the frame from 1080p to 720p sucks up more resources, causing the drop in FPS? Remember that the source is 1080p... Reply
  • tential - Monday, June 03, 2013 - link

    Ok so if I'm downscaling to 720p, why does FPS increase with quicksync, but decrease with the processor?

    It's OPPOSITE directions one increases (quicksync) one decreases (cpu). Wouldn't it be the same both ways?
    Reply
  • ganeshts - Monday, June 03, 2013 - link

    Downscaling is also hardware accelerated in QS mode. Hardware transcode is faster for 720p decoded frames rather than 1080p decoded frames. The time taken to downscale is much lower than the time taken to transcode the 'extra pixels' in a 1080p version. Reply
  • elian123 - Monday, June 03, 2013 - link

    Ganesh, you mention "The Iris Pro 5200 GPUs are reserved for BGA configurations and unavailable to system builders". Does that imply that there won't be motherboards for sale with the 4770R integrated? Will the 4770R only be available in complete systems? Reply

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