Just a quick refereence to the OPs question. The software to integrate screens and comps is called "multiplicity". This allows for a single workstation/operator to use two or more comps with multiple screens. Pretty cool for those who want the computing power of multiple computers without switching keyboards and such. Anyway, sounds like that isn't the best solution for the OPs situation. Just thought I'd mention it.
IMO, the best solution is to run 4 video cards. Each has its own memory and you get better performance that way.
Thanks Gnome, You're always good for help. Thank you! I think I meant to say "Y" cable instead of splitter. Can you recommend any basic dual head video cards with Y cable that I can use for my 4 monitor purpose?
Not really. I've run 4-card, dualheads, dual + singles... If the cards are good, it's all the same for trading. Best overall solution for 4 monitors is probably Nvidia Quadro NVS. Matrox is OK, too... but the Matrox Millennium cards are slower. (Matrox has a new line out... functions and looks like Quadro NVS, but more expensive.)
Nvidia Qudro NVS... What kind of mobo do you have... AGP or PCIE? If your mobo is AGP, you'll want NVS 280 AGP + 280 PCI cards. If mobo is PCIE, you'll want NVS 285x16, and either 280 PCI or 285x1. (If your mobo has 2 or more PCIEx16 slots, you can just use x16's.) You can also use quads, but they are expensive.
I think its PCI-E. I just bought a new Dell slim model with the video card on the motherboard so there's a few slots to add new video cards. I think there's a PCIx16 and another PCI slot. Does that help you? I just need to be able to add 3 more monitors on top of the default one on the agp port.
If you have PCIEx16, than you don't have AGP slot.... it's either one or the other. Having onboard video might be a problem... depends on the BIOS. You may find it easier to disable the the onboard video and just use the PCIE and 1 PCI slots.
You're probably OK. If a PCIE slot is on the mobo, they intended for the user to be able to disable the onboard if desired. Your mobo probably has either 1, PCIEx16 + 2, PCI... or 1 PCIEx16, 1 PCIEx1 + 2 PCI. Unless your other slots are taken up with things like modem, sound card, TV tuner or controller, you probably have enough to run 4 monitors.
I was assuming that the person wanted capabilities beyond simple trading platforms. I have some pretty intense CAD systems running. Shared cards don't work as well for me. Maybe I just haven't found a good one yet though.