i have an 8400 gs in my computer but i want to run a 3rd monitor (not all the time, just when i want to do blender stuff.) and i also have an old fx 5200 ( not likely to work) pci car and an old radeon pci-e (really not likely to work) card of some sort. Is it possible to run them side by side? I would think i'd need identicle cards but I don't want to dump any money into my computer. Just to clarify I don't expect any kind of performance increase just another monitor.
Yes, you can run extra monitors from another completely different card. I haven't tried it, but I have seen it done many times.
Yes, thats how I have my two screens working. Running a HD6950 and a 8600GT btw. The only thing you can't do is play with Eyefinity/Tri-screen thing.