Hi Eric,
what is the actual specification of your PC? What processor do you have, how many 'processor cores' does it have and what is its clock frequency? What OS are you using and how much RAM do you have. How much RAM does your graphics card have? What is the reresh rate for your graphics card?
You will need plenty of ram to handle full 4K resolution of 3840 x 2160 pixels. If each pixel has 3 (R, G and B) values associated with it, and each pixel can have 256 'shades' in each of those three colours. then you have the often-quoted "16 million colours" (256^3, or 16,777,216 colours to be precise). So every single screen update needs 3840 x 2160 x 3 bytes of data to be shifted out from the PC (24,883,200 bytes - or roughly 24Mbytes)
If you have a refresh rate of, say, 100Hz, then that means you are shifting that amount of data 100 times per second - the arithmetic would then suggest that you have to stream data at almost 20GHz - which is pretty impressive!!
However - most systems would be totally incapable of streaming data at that rate. Fortunately, there are algorithms that can 'squeeze' the data down prior to sending it to the monitor, and the monitor recreates the image once received. Of course, you still then need a very impressive processor in the monitor to perform both the decompression and the streaming of the image onto the actual screen itself - technology that is way out of my understanding!!
If you are having better results when 'scaling down' you image data, then this does tend to suggest that you can't process the full-scale data due to system restraints (hence the readon I wa asking about your basic system specifications).
Perhaps other who have gone down the 4K route might share their experiences - and give us an idea of what specifications they had to exceed in order to get a stable system.
I'm still running an 'old-school' PC here - but, it was 'top-of-the-range' at the time (a Quad-Core Intel CPU at 3.4GHz, with 8Gb of DDR2 RAM and an nVidia GeForce graphics card with 1Gb of RAM). I can happily stream full 2K resolution images all day long - as well as support two other monitors at 720p on a second nVidia graphics card. I did find that my biggest bottleneck was hard-drive access - so I now have 6 x 750Gb Crucial SSDs in the machine, thus all but eliniating any latency due to hard-drive read/write times. I also upgraded all three of my external NAS storage to RAID arrays (dual, mirrored) using the original six 2Tb HDDs that came out of my PC during the SSD upgrade. I have no idea what to do with the original six 1Tb drives - I may just throw them into an external JBOD array - but there is only so much storage that a man can ever need (16Tb, spread all over my property, including outside in a shed as well as the observatory - you can never be too paranoid about a drive failure that results in you losing all those critical dark frames!!!)
