I recently forked out for a 4K TV to try out as a monitor on my PC. Despite reading a number of reviews that 4K TVs didn't work very well as monitors I was undeterred and went ahead with the purchase anyway. If it had been no good I would have just ended up with a new TV for the bedroom. As it happens things went better than expected.
£500 for a 40″ display capable of 3840×2160 at 60Hz is a lot screen for the money. Articles I'd read online previously pointed to poor image crispness when used as a PC display, with blurry pixels and fuzzy text making them very difficult and uncomfortable to use. Granted these reviews seemed to centre around a bargain basement model released by Seiki (who?). One article in particular that did a good job of putting me off was this one.
As I'd got a plan B for the TV if things didn't work out (I needed a new one for the bedroom) I decided to go for it anyway.
Long story short, I'm glad I did. The image quality is amazing, easily as good as my 24″ Dell IPS monitors. Text is sharp and easy to read, albeit a bit small. It can be scaled up by changing Windows settings, but to be honest, 3 feet away like I am, it is perfectly usable. Gaming on this monitor is awesome and has pretty much completely removed the need for nVidia Surround for me.
The model I purchased was the Samsung UE40JU6400. Not only does it make a great monitor, but it's also a Smart TV so I'm able to run the Netflix and Amazon Instant Video apps on it (among many others). It also features built-in WiFi, so there's no need to buy a dongle and there is also a wired Ethernet port.
My only gripe about the TV itself is that the wired Ethernet port is only 100Mbps. You would think in this day and age everything would have Gigabit Ethernet, but sadly this is not the case. Not that it seems to make much difference, I am able to stream 4K Amazon content without issue and it looks amazing.
The other main con, is graphics card output / cabling compatibility. As it happened I was in the market for a new graphics card anyway, but I wanted to see if I could get the Samsung running on my old GTX690.
The GTX690 has 3 x DVI outputs plus a Mini Displayport 1.2 output. I'd already got 24″ monitors connected to the DVI ports, so first I tried a MiniDP to HDMI cable from the card to the TV. Nothing I did made the display go to a higher resolution than 1920×1080. I tried a MiniDP to HDMI dongle with a straight HDMI cable too, but no luck their either.
At this point, I decided to order a new GTX 980 card anyway, which has 3 x DisplayPort and a HDMI output. At the same time I ordered a good quality HDMI 2.0 cable, and that setup worked absolutely fine.
In conclusion I would absolutely recommend this TV for use as a PC monitor. Just make sure your graphics card is up to the job and that any cables you buy are of the right spec and decent quality.