I don't really know a lot about power supplies but I was wondering if it was possible to run two graphics cards with my power supply.
My current set up is
Processor: Core 2 Duo 2.33Ghz
Ram: 4x1gb DDR2
Video Card: ATI Radeon HD4890
Power supply: Cooler Master eXtreme Power Plus 460W
Not too sure about my hard drive speed etc. but its model number is WDC WD32 00AAKS-22SBA SCSI Disk Device
With 24" and 19" monitors attached to the HD4890.
Basically I want to use my old 8600GT for my 19" monitor so I don't lose any fps on my 24" while playing games.
Just checking that I won't completely destroy my system
The general rule of thumb is a high quality 500 to 550 watt power supply with sufficient current (amps) on the 12 volt rail(s) can easily power a system with any single video card made. A high quality 700 to 750 watt power supply with sufficient current (amps) on the 12 volt rail(s) can power just about any system with two video cards operating in dual mode (SLI or Crossfire). For example, two identical cards would be used together to play a game. The idea is to enhance performance while gaming.
If I understood you correctly, then what you are asking is not dual mode. I can't recall any article or thread about using two different video cards in one pc for two different monitors. I am not prepared to say it's impossible. I just never heard of a configuration like that.
However, what exactly happens if the PSU cannot supply enough current to power the hardware. Does it just not work or can it damage components.
Random restarts or you end up frying something. You are essentially pushing your PSU to its limits. And when a component (for you, a video card) doesn't get enough juice, you can expect restarts or your PC might not even boot to windows.
Spec everything out in terms of power consumption. You should be able to find everything from their website. If the total is 80% or more of your PSU's rating, you need to upgrade. Keep in mind PSUs will say they are a 500 watt supply but truly rated at say, 420 watts. Such is the case for my Thermaltake PSU.
Lastly, I would agree with Johnny. I haven't heard of two different cards being used; especially from two different vendors.
I've asked about using a cheap NV card for physics to complement my 4870 and was told it was a no go, but can't find the thread.
I know that if you change video card manufacturer you should clear all traces of the previous driver or face reliability problems. I would assume the same applies here. I'd be happier going for another cheaper AMD card than mixing it up.