There's one thread about that here..You may run into compatibility issues with anything newer than a 600 series card with the old 790i..You can still find older stuff here and there but you'd need to search around for them, there's a few at Newegg.
 
If you're on a very tight budget, you might consider trying to fix the 280 for the time being..You can disassemble the card, clean it up and bake only the PCB like this and hope for the best..Solder cracking somewhere on the PCB is a common cause of graphics card failure and can cause artifacting, BSOD, POST fail, garbled text in BIOS/POST, system freezing, black screen, driver timeout/reset/crash, Device Manager error codes or other issues..If solder cracking is the problem (which it probably is, almost guaranteed), baking should reflow any cracks that might exist and that will fix it..It's important to bake it with the GPU side up and in the center rack of the oven..Baking may fix it for a while or for a long time and sometimes is required more than once..Do not substitute thermal paste for thermal pads..There's a few disassembly guides you can search for online if you need..There's a few guides on YouTube also.
 
If it's under warranty you could see about an RMA..The AR suffix cards have a lifetime warranty.

You're welcome..I figured the "oven trick" would fix it..Hopefully it will last a while..I've had cards that I baked and they worked okay for varying periods of time until the solder eventually cracked again causing artifacts/BSOD, so  I would bake again to fix again..If you don't have EVGA Precision or MSI Afterburner, you should get one or the other and make a custom fanspeed curve to help keep the GPU temp down..Solder cracks are caused in large part by thermal stress.
 
Yeah, the good old 790i boards are pretty much obsolete and in legacy status now and it's a pain, or even impossible to get new/newer hardware to play nice with them sometimes..Used to have a 790i FTW running a Q6600 @ 3.6GHz myself.