I recently purchased a 4k tv to use as a monitor.
I was easily able to get it to work at 30hz by using the windows screen resolution dialog.
However, it took me awhile to get it to work at 60hz - the trick was I had to use the NVIDIA Control Panel. This was on Windows 10.
When I did this, it also hid a drop down that allowed me to switch the color from between 4:4:4 and RGB. I am guessing that this is because my tv only supports 4:2:0 at 60hz.
Unfortunately, as soon as I switched to 60hz, I noticed a number of additional problems.
1) Certain windows would flicker (like they were being redrawn slowly), but others not all. For example, the task manger would flicker quite heavily. The NIVIDIA Control Panel flickered a little bit, and some other programs, like MS paint, did not flicker at all.
2) The text mouse cursor, the one that looks like an I beam, got clipped so only the top half was visible - it looked like a T shape. The standard white arrow looked fine - as did all of the resize/move cursors that I saw (although I will admit I probably didn't check every possible cursor that exists).
3.) The mouse cursor did not move smoothly - I was definitely getting 60hz refresh rate for some things. The tv said it was getting a 60hz signal, and I used the UFO Test on the Blur Busters website. The mouse, however still basically looked like it was moving at 30hz.
Link:
http://www.testufo.com/#test=framerates
While I was messing with the windows graphical options, I noticed something very strange - if I ran the windows magnifier application, all of these problems disappeared, and everything was basically working fine. As soon as I closed it, all 3 of the above problems reappeared.
*Note that you don't actually have to DO anything with the magnifier other than have it open. I set the view to "full screen" and the zoom to 100% which does nothing at all - well, nothing except fix the aforementioned bugs.
I used NVIDIA Shadow Play to record this (although I haven't uploaded the video anywhere because even though its less than 20 seconds long its still quite huge since it's 4k, and I expect that it would get down sampled quite a bit regardless) Anyways, on the shadow play recording, it recorded exactly what I saw, with the exception of the T instead of I as a text cursor issue - it showed the correct I on the video.
Anyways, at this point I had become quite frustrated with Windows 10 in general (main motivation was that I couldn't get javascript to work, but that's neither here nor there), so I Downgraded back to windows 8.1 before my 30 days ran out.
On windows 8.1, things were actually a little better.
After fiddling a bit to get it running at 4k 60hz, it was working pretty good - the task manager no longer flickered, and the mouse pointer seemed to move smoothly at 60fps.
The only problem that remained was the I shaped mouse cursor, which didn't look like a T this time, it looked like it had been shrunk slightly horizontally with a really terrible algorithm - the vertical bar was gone so all that remained was the top and bottom of the I, which seemed a tiny bit skinnier than normal, and were a little discolored. (This made it really hard to see)
I also had a problem with the black border of the cursor disappearing when i RDP'd into a windows server 2012 server for work. The mouse was usable mostly, except that it would effectively disappear completely when against a white background. (I did what I needed to do for work and I am logged off now, and I didn't bother to test the magnifier fix for work. I will update when I do, but I kinda expect that it will fix it.)
I tried to remedy this by switching to different mouse cursors, and I may have gained a little insight into the problem - it seems that the mostly white cursors work fine (ex: the default arrow and move cursors) but the mostly black ones are distorted and miscolored. I switched to the black cursor theme and my normal mouse pointer ended up looking like the screenshot in the first post of this thread: https://forums.geforce.com/default/topic/780518/4k-60hz-weird-graphical-cursor-bug/ (If that link disappears - the cursor is squashed horizontally and discolored.)
Now, this is Windows 8.1, but I figured I would try the magnifier fix again. Indeed, it worked, and as long as I keep the application open.
Also, in the thread on the geforce forms, someone mentioned turning on pointer trails. That seems to fix my I cursor issue, but I despise cursor trails so I would rather just leave the magnifier open all the time.
TV:
JVC TV LT-42UE75
42" Class 4K Ultra LED HDTV
Video Card: EVGA GeForce GTX 980 SC
Cable: HDMI High Speed
Does anyone run windows 8.1 or 10 at 4k 60hz and get the correct mouse cursors all the time? If so, what did you have to do to get it to work, or what hardware are you using?
