Looking to upgrade from GTX 580

I don't know much about SolidWorks but a quick search reveals this program runs way faster on workstation GPUs - Quadro and FirePro series.

In this chart (http://www.tomshardware.com/charts/workstation-graphics...), a $165 AMD FirePro V4900 is barely slower than an $800 Quadro 4000. Sounds like AMD's FirePro cards offer way better price/performance for this application, but you are going to need to do more research.

Even at 4xMSAA, V4900 seems to provide unbeatable price/performance:
http://www.tomshardware.com/charts/workstation-graphics...

ATI FirePro V4900
http://www.amazon.com/dp/B00653OOPS/ref=asc_df_B00653OO...

Maybe you are better off getting 2 Fire Pro cards and sticking them into your other X79 slots and selling your GTX580s and upgrading to GTX780s next year separately for gaming. It seems that the regular consumer GPUs would be way slower in this app against dedicated workstation GPUs. It's up to you to do additional research but my quick browsing online shows SolidWorks is really not great at all on consumer GPUs. You would be seriously wasting $ on consumer GPUs for this program. I'll show you what I mean:

HD7970 ~ $360
W5000 ~ $430 (http://www.amazon.com/AMD-2DisplayPort-PCI-Express-Work...)

Benchmarks:

$1,300 W8000 = 68.76 fps
$430 W5000 = 58.59 fps (Based on Tom's benchmarks, Nvidia's Quadro 4000 which costs $700 only got about 35-38 fps.)
$360 HD7970 = 29.16 fps
http://www.legitreviews.com/images/reviews/2070/SPECvie...

and this review:
http://www.legitreviews.com/article/2004/1/

That tells me the W5000 is the sweet spot on the AMD side for this program, but even a $165 V4900 is as fast as a $360 HD7970. This guy on the SolidWorks website says the price/performance of V4800 is insanely high (https://forum.solidworks.com/thread/61773) and there is now a 4900 for $165.

Based on the review just above, V8800 got replaced by W8000. You can also pick up V8800 for about $880 or $675 used:
http://www.amazon.com/100-505603-FirePro-V8800-Graphic-...

But then you can get 2x W5000 instead? Does this program use both GPUs if you have them? Are W series much faster than V series because of Graphics Core Next optimizations for SolidWorks? More research is required.

If you look at consumer GPUs, essentially if you got an HD7970 x2, it would only be as fast as a single W5000 card for nearly double the cost! I am sure things are even worse for GTX680 vs. Quadro since GTX680 is a crippled card for professional work/compute and in many ways worse than GTX580 for this type of work. Do your research to compare GTX680 vs. Quadro 4000/5000/6000 and see how that stacks up against V4900 FirePro for $165 or W5000 for $430. I wouldn't even be surprised if a single W5000 outperforms both of your 580s in this program since it seems specific workstation drivers are critical here.