Monitor and Graphics Card Issues

[FanOfWulves]

New here!
Anyway, here is my issue.
Was on my computer playing SIlent Storm Sentinels when green vertical bars suddenly covered the screen followed by the computer turning off. The same bars came back when I turned it on and I can't get past the start up screen. Changing monitors did not fix it so it must be the graphics card. I tried my brothers card and even bought a new card (brother's same as mine) but the monitor just remains black with the LED blinking. When using my original card it shows green lines again. It does not say there is an issue with the signal, and my brother's card and both monitors work fine on his PC. I am at a loss! I just want to use my computer again!
Specs:

AMD Six-Core FX-6120 Proccessor
Old graphics: Radeon HD 7450 w/ 1GB DDR3
New Graphics: Radeon R7 240 w/ 4GB DDR3
Memory: 10GB DDR3
Monitor: Samsung Syncmaster S20B350
PSU: EVGA 600watt

If you need any more info, tell me!

Update: I tried the new card in my brother's PC and it works fine there as well. Therefore, does that mean that something other than the card and the monitor is responsible?

Next Update: I'm convinced something is wrong with the computer itself as it seems to be unable to actually get past its starting up phase. Gah!

 

[nvincent_08]

how about the driver and perhaps the bios? have you updated them all??

 

[Ryan Reynolds]

i would say that it is time for a new gpu. seeing what you are currently using i assume that you dont want to spend a ton of money so i would get this https://www.newegg.com/Product/Product.aspx?Item=N82E16814202289&cm_re=rx_560-_-14-202-289-_-Product
hopefully this helps. usually artifacting on a gpu means that it is dying.