Re: Soldering new memory chips on a video card
Don't bother. Video cards use a special type of RAM chips called BGA chips (ball-grid array). These chips have pads on the bottom where the solder attaches and holds the chip to pads on the surface of the board. Normal soldering skills are useless here, as they can't be desoldered from the other side of the board and they're not normal surface mount so you can't even desolder from the top. The only way to work with them is using a special reflow station that passes hot air under the chip to melt the balls of solder. This same method is used on the XBOX 360's graphics chip, RAM, and CPU, and is the reason behind the infamous Red Ring of Death, as the balls of solder crack under the chips and you can't reflow the solder without a special tool (most fixes resort to conventional heating methods, such as a heat gun or overheating the chip until it kicks the thermal shutoff). You could try the same methods on your card (try blowing hot air on the chips, apply a bit of pressure, etc) but I doubt it'll work. Your chips are probably internally damaged, though replacing them will be incredibly difficult. I'd say RMA it if possible, but otherwise you'll just have to live with it or replace it altogether.