Respond please, I need help ...
The usual causes for that are:
1. Bad VRAM clock , OR your card's VRAM is on its last legs (card about to die). If you overclocked your card, you can try lowering the clock on the VRAM, but usually when that happens because of VRAM the card will soon be finished. (Most likely)
2. Power Problem of some sort (Common, probably likely)
3. Card needs to be reseated or your PCI slot might be bad. What you can do is turn your PC on its side (with the card facing up) and see if that helps with the problem. I have a card that is physically cracked that does the same thing (poor design caused the card to crack under normal use). The solution was putting it in that alternate position. (Worth trying, see link below)
A picture for referece, courtesy of Overclock.com:
4. CPU and RAM - CPU and RAM OCs can cause that problem, however you said that your other card didn't reproduce the error so its not likely to be this.
5. Driver (rare) - if you recently updated your driver, you can try installing an older driver. Other PCI device drivers (like a Soundcard) can cause issues as well, but its extremely rare.
I assume your card is several years old, and by the looks of this stripes i can say in most cases this is hardware problem. If you already tried to reinstall the drivers, change cables and such, clean your card etc, one last thing you could do is test your 7870 in other PC to confirm that problem still exist. But as i said previously, it's high chances your GPU is dying. I'm sorry
If you provide some extra information about first appearance of this stripes it can help to solve this problem - or not.
Thank you very much for answering, I'm figuring out a new plate then greetings