I'm a bit worried about Dual-slot GPU's and my motherboard. I have the Gigabyte GA-P55M-UD2 and it has two PCI-E slots; but one is x16, and the other one is only x4. I was hoping to splash out on a fancy graphics card soon, but since most good ones are dual-slot, what kind've performance loss can I expect running half the gpu on an x4 slot? I've read it can be up to 30%, which is a bit depressing. Does anybody else have this concern?
Dual slot just means that the card takes up two blanking plates on the rear of your machine and potentially blocks one internal expansion slot, not that the card itself uses two PCI-E slots. You'll be fine for a single card config, not so much for a CrossfireX/SLI config though.
digitaldunc explains it well. Here is a picture comparison: Single slot: The above is common, today, they are considered mid to low range graphic cards in term of performance. Dual slot: Notice how thick the graphic card is. These are usually high performance graphic cards, as these model of graphic cards heats up A LOT, a large fan and heatsink is needed to operate. They are twice the thickness of the first graphic card shown on the picture above. Notice that is only has 1x connector at the bottom that connects on your motherboard, just like the previous model shown, it's just thicker. You insert this graphic card on your PCI-E 16x slot. (so basically you need to remove your current graphic card, and slide in the new one). Please note that the high end graphic cards requires additional power, that needs to be connected. Without it, it wont' work. Based on the graphic card the connector can be different. Just make sure your Power Supply has the power cords to connect to it. Your computer will NOT turn on successfully, if your graphic cards doesn't have those additional power plugs connected to it.
Nvidia have done it on a few cards, it you don't give them enough juice they scream their nuts off and change colour. It's pretty similar to me down the pub.
Thanks for your genuinely constructive response Goodbytes; I don't have any experience with a graphics card over £150 so wasn't sure when I read this article with the heading of dual slot card and seeing what looked to be two pci-e slots at the base of the card. I know it's only a press photo but as I say, I've never even seen a pricier card before so didn't know what to expect.
The angle on that photo does give the impression of a second connector! Easy to see how the confusion occurred. At least now its understood!