If you want to run Folding at Home with more than one graphics card connected, then if you are using Windows Vista, you will need a monitor attached to each graphics card, or use a dummy plug to make it seem so. You need to tell Windows to spread the picture over all your graphics cards. Windows XP will happily assume each graphics card has a monitor attached and try to spread the picture over a monitor which you do not have. Windows Vista checks to make sure. You can make a dummy plug using three resistors and either a 15-pin D-plug or a DVI-I to VGA adapter, which is included with most graphics cards. You can solder the resistors to the 15-pin D-plug, or simply stick them in the holes of the DVI-I to VGA adapter. Here the link to the diagram you are going to need so you know where to put your resistors. http://soerennielsen.dk/mod/VGAdummy/index_en.php is the diagram. Actually, you can get away with only having the middle resistor, the one connecting pins 2 and 7. But at some future date it might not work and you won't remember why. How does it work? The graphics card sends separate picture information on three separate channels, red, green, and blue. Each of the three channels has a pair of pins pin 1 is Red Signal pin 2 is Green Signal pin 3 is Blue Signal pin 6 is Red Ground pin 7 is Green Ground pin 8 is Blue Ground If there is a monitor attached, it takes a few milliamps of current from the graphics card. The computer tests wether a current is flowing from the Green Signal on pin 2. If there is, it is assumed that an old-fashioned VGA or SVGA monitor is connected. The resistor connecting pins 2 and seven causes the same amount of current to flow as a monitor would. Why 75 ohms? If you are sending water down a pipe, it flows smoother if the pipework is the same diameter all the way. If you are sending electricity at radio frequency, it flows smoother if all the components have the same impedance. Television gear has an impedance of 75 ohms. In the UK, Maplin M75R metal oxide resistors are the easiest to buy, but the wire is a bit thin to stick in the holes of a DVI-I to VGA adapter. It is said that 1/2 watt carbon resistors have thicker wire that is just the right size. In the USA, 75 ohm resistors are harder to find. You can use 68 ohms or 82 ohms instead. Anything between 50 and 100 ohms will probably work. If you use less than 50, you will be drawing too much current, perhaps. If you use too high a value, perhaps not enough current will flow to simulate a monitor being connected. It does not matter which end of a resistor is which. I have arranged mine like this so you can see the colours are the same, and the bodies stop the wires touching. You only need one dummy plug per graphics card, even if it has two monitor sockets. Windows tries to detect what model of monitor is attached, and fails. Windows XP calls it a "Default Monitor" and Vista calls it a "non-generic pnp monitor". Resistors stuck in DVI Adapter, wide part of VGA socket uppermost. Resistors stuck in DVI Adapter, view from other side. Close up of Maplin M75R resistor. violet, green, black, gold, brown. The top three colours should be the same whichever type you buy. The other two colours show the tolerance, which does not matter.