Weird graphics bug, blocks of the screen has issues updating

[Danicco]

Hi, a while ago my screen started showing some weird issue where parts (like blocks) of it seemed to update slower than the rest of the screen, and these affected "blocks" would change in size during the issue.
Whenever I move the mouse over these blocks it's as if there's a ghosting effect on the cursor, but not a pretty one. It seems those blocks gets stuck with an image and can't properly update to the newer image, going back and forth.

I tried googling for potential graphics issues but I couldn't find anything like this issue. Or I don't know how to properly google for this issue.

I tried changing the HDMI cables, didn't help.
I suspected it could be related to the graphics card because it coincidentally started after I opened my PC to clean some dust, I do this about once every couple months, since I removed the GPU and then plugged it back.
I recently got a new TV and it could probably be the cause too.
The issue happens randomly, sometimes I go for a couple of days without issue and then some days I get it on multiple occasions.
It has happened on various situations, while gaming, watching videos or simply browsing my folders.
To "fix" it, I can either change the resolution (windows or ingame), reset the PC, unplug/plug the HDMI cable or change the TV input then change back.

My TV is a Sony X850C, about 1 month old. I set the signal to "Enhanced HDMI" on the options.
My GPU is a Gigabyte Geforce GTX 970 G1 Gaming, about 6 months old.
I'm almost positive the issue is with the GPU, but I don't know how to be sure or fix/test it.

Any ideas what could be causing this or any kind of test that I can try to figure this out?
I'm out of ideas and I still have no clue how to fix/figure this.

Edit: Driver version is 368.81, I just noticed it's not updated, I'll update it and check if this issue happens again.

 

[hang-the-9]

Since you have several variables, new display, opening the case and removing the card, need to rule things out. Does this happen if you go back to the old display? You should monitor temps and see if anything is overheating. If system is overclocked, set it to stock speeds.

 

[Danicco]

Since you have several variables, new display, opening the case and removing the card, need to rule things out. Does this happen if you go back to the old display? You should monitor temps and see if anything is overheating. If system is overclocked, set it to stock speeds.

Testing the old display is a bit tricky, because I can't control/reproduce the issue at will, it really goes at random.
Sometimes it happens when I'm playing LoL, a relatively undemanding game, and it also happens when I'm playing a Tomb Raider or Metro on high settings.
So I guess it isn't related to how much the GPU is in use.
After some days without issue, it happened today while playing FFXIII on an area where I was having FPS drops, and I checked the temperature and it was around 50º. After the issue was gone, I checked the temp. again and it was still the same.

I used some GPU tests (Heaven, 3D Mark and FurMark (even though it's unadvised)) and they went without a hitch.
I tested with various configurations for quite some time with the Heaven Benchmark, but nothing happened.
Nothing in the system is overclocked.
Drivers are properly updated too.

These issues that I can't even reproduce really drives me nuts...

 

[hang-the-9]

You can try a clean Windows setup with new drivers to rule out any software issues. Aside from that, image artifacts are most often caused by video card issue. Maybe try a different cable. Maybe the power supply especially if you have a low quality one.