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Old 23rd July 2014, 00:49   #26972  |  Link
JarrettH
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Join Date: Aug 2004
Location: Canada
Posts: 860
Quote:
Originally Posted by Asmodian View Post
I did a madVR performance test on my Titan with Jinc3+AR/Jinc3+AR, smooth motion on, debanding low/low, ordered dithering. 4 frame rendering buffer, 1 present queue, windowed mode (new path), Windows 8.1. SLI Off.

1080p24 -> 3840x2160@60Hz, 17.5ms

While playing Nvidia Inspector says:
GPU 41-52%
MCU 10-14%
GPU CLK 549-679 MHz
RAM 1429MB

Assuming performance is directly proportional to shaders*MHz a stock GTX650Ti has 39% of the GPU performance of a Titan @ 679 MHz. It also has 28% of the memory bandwidth of my Titan, well above the 14% I used.

This works out to at worst a 25.9ms rendering time on a GTX650Ti at 90% GPU usage; fine for 30fps or lower but not 60fps (16.6ms).

If I use Bicubic75+AR for chroma scaling and Jinc3 for image it changes to a 15.6 ms rendering time with at most 44% GPU usage. Scaling to a 19.5ms rendering time on a GTX650Ti @ 928MHz and 90% usage. Still not enough for 60 fps but plenty of headroom for 30 fps (33.3ms).

These are worst case estimates though, I wouldn't be surprised if the GTX650Ti had the GPU power for Jinc3 Image and Bicubic75 chroma for 1080p60. Sadly the memory bandwidth is probably insufficient.

Memory usage is a major issue though; if I turn the buffers down to 4 rending and 1 present I still hit 1429MB of GPU memory used and 4/1 is the minimum.

Edit: I was able to get memory usage down to 958MB with Jinc3+AR chroma and Jinc3+AR image by turning on most of the trade quality for performance options (10 bit instead of 16 bit) and turning off debanding and smooth motion.
Speaking of rendering times, how do I know what to aim for? My refresh rate is 60 hz. Where did 16.6 ms come from?
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