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Full Version: Theory about reducing multi-display idle clocks
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I have a 3 monitor setup. 2x 1080p (60Hz) and 1 UHD (60Hz). I recently became aware of the behavior of GPUs to idle at their base clock with this type of setup, and since then I have been searching for a solution.

Recently, I came across this forum, and the answer I have seen here is that the memory clock needs to be high to allow it to switch fast enough to compensate for the differences in vertical blanking between displays. What I want to know is, theoretically, could I give the card more time to switch by increasing the vertical blanking of my UHD display? (and thus maybe allow it to downclock) I thought I'd run it by you guys before I just went and tried it with my displays (see the link below).
No, the answer is the memory clock can't change if the vertical blanking is too low because there won't be enough time between refreshes to retrain the memory without visible screen corruption, but that's when dealing with a single monitor. If you have multiple monitors, all of the monitors must be perfectly synchronized so the vertical blanking happens at the same time on all of the monitors, otherwise it's impossible to change the memory clock without affecting at least one of the screens. In theory, if you change the UHD monitor to use "Automatic (HDTV)" timing for 3840x2160 @ 60 Hz, then it should be perfectly synchronized with 1920x1080 @ 60 Hz (the pixel clock will be exactly 4x), but I don't know if the driver will handle cases where the resolutions don't match exactly, so there's probably no way to make this work. The resolutions already have enough vertical blanking time, so changing that won't make a difference.
Thanks so much for the reply, i was hoping to get an answer from you. (you seem to be the only one on the internet that has any knowledge about this issue. at least that ive found in several hours of looking.) Ill try the idea with "automatic HDTV", I'm willing to at least test a theory. I was if syncing them up would potentially fix it anyway, i just didnt know enough about the various settings to know what to set it too. ill let you know if it works (cause that would be awsome)
HAHAHA!!!!! IT WORKED!!!!! My Card now idles at 300MHz and my memory sits at 405 MHz. (significantly better than the 1350MHz and the 7000MHz that it was sitting at when at idle). Just to be clear if anyone ever comes across this looking for an answer. I switched my UHD display to "Automatic (HDTV)" and now it idles! Thank you so much ToastyX!
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