LG Ultrawide Monitor - Resolution Issues

Hi,

I have a 08' Mac Pro that I use everyday and I got sick of my old dual screen set up. So last week I ordered an LG 25UM57. I've heard good things about LG's ultrawides, but I can't get the **** resolution to look right at 2560x1080!?

I'm running El Capitan 10.11.6 which is the newest OS my machine can support apparently. I heard many people had problem just like this while running macOS Sierra, I don't think outdated OS is an issue. I also have a Nvidia Quadro FX 5600 GPU which is capable of 2560x1600. And I have a "4k capable" Dual-link DVI to HDMI adapter with HDMI going from the adapter to the monitor. Sounds right? No. It looks horrible. The weird thing is, images and video look great. But any text or other sorts of graphics are so aliased they're nearly unreadable and the smaller it is, the worse it is. Here's a pic of some text - https://ibb.co/mDVjCF

I've tried SwitchResX which a lot of forums have recommended and supposedly this works for lots of people. But not for me, same result. One last weird thing. Even when SwitchResX says it's giving me 2560x1080 I get a message from the monitor itself that says it's only getting 1920x1080. https://ibb.co/mgj3pv ...I don't get it.

Any suggestions? Please help! I love the ultrawide and don't want to have to return it! Thanks.