HTPC Aspects : Custom Refresh Rates

AMD and Intel GPUs don't offer the end users an easy way to create custom refresh rates for their displays. While Intel does offer a control panel for custom timings, it is heavily tied to the EDID, rendering it unusable for the most part. On the other hand, AMD GPUs have had a history of being close to the desired refresh rates out of the box. NVIDIA's GPUs have always needed some tweaking, and the Zotac GT 640 is no different.

As we have recounted in earlier HTPC reviews, a GPU should ideally be capable of the following refresh rates at the minimum:

  •     23.976 Hz
  •     24 Hz
  •     25 Hz
  •     29.97 Hz
  •     30 Hz
  •     50 Hz
  •     59.94 Hz
  •     60 Hz

Some users demand integral multiples of 23.976 / 24 Hz because they result in a smoother desktop experience, while also making sure that the source and display refresh rates are still matched without repeated or dropped frames. The gallery below shows the refresh rate handling for 24, 25 (x2 = 50 Hz), 29.97 (x2 = 59.94 Hz), 30 (x2 = 60 Hz), 50, 59.94 and 60 Hz settings.

The native 23 Hz setting, unfortunately, resulted in a 23.9724 Hz refresh rate.

However, with some custom timing setup, we were able to achieve 23.97622 Hz, which is off by just 0.000196 Hz. In my experience, this is the closest to the optimum refresh rate that I have ever achieved with a NVIDIA card.

The custom timing feature is usable, but not without its quirks. Adding a custom resolution is straightforward. Setting the vertical parameters to values similar to the ones in the screenshot above achieves desired results, but the 23 Hz resolution gets saved as 24 Hz. We already pointed out the details in our review of the GT 540M in the ASRock Vision 3D 252B. We hope NVIDIA fixes this annoying issue in one of the upcoming driver releases.

HTPC Aspects : 4K Decode and Display HTPC Aspects : HQV 2.0 Benchmarking and Video Post Processing in Action
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  • extide - Wednesday, June 20, 2012 - link

    For posting folding benchmarks! A lot of people really appreciate that!
  • Zink - Wednesday, June 20, 2012 - link

    No one else uses your benchmarking tool and it doesn't always correlate to performance with current F@H projects but that is the only reason I care about GPUs.
  • Marlin1975 - Wednesday, June 20, 2012 - link

    Good design if it had DDR5. If they can do 2gig of DDR5 then it be a great mid-price card.
  • Homeles - Wednesday, June 20, 2012 - link

    It would still be terrible until the price dropped.
  • Samus - Thursday, June 21, 2012 - link

    There's no reason this wouldn't be similar in speed to a GTX460 if it had DDR5. The only difference would be 128-bit vs 192-bit memory bus, everything else would be an advantage: same number cores, substantially higher clock speed, lower power consumption increasing overclocking headroom, etc.
  • MrSpadge - Thursday, June 21, 2012 - link

    You forget: substantially lower shader clock speed, more coarse shader grouping -> more difficult to use them all at once, and software scheduling -> need a better compiler, can't do runtime optimizations.
  • t_case - Wednesday, June 20, 2012 - link

    So who has the Sony VPL-vw1000ES? Now that's a nice projector... only roughly the price of a new car heh.
  • stephenasmith - Wednesday, June 20, 2012 - link

    I love me some painfully slow gaming!
  • nitrousoxide - Wednesday, June 20, 2012 - link

    Just curious if the most powerful IGP can keep up with entry-level Kepler
  • Roland00Address - Wednesday, June 20, 2012 - link

    But this should get you an idea of what performance you would be getting with llano. (Numbers taken from Llano review that appeared 12 months ago so drivers will be old.)

    Crysis Warhead 1680x1050 performance quality
    A8-6550D with 1600 mhz memory
    58.8 fps
    A8-6550D with 1866 mhz memory
    62.5 fps
    99.8 fps

    This makes the 640 about 69.7% faster than a non overclock Llano (people are going to get 1600mhz memory).

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