I'm thinking that the card is smoked. I came home one day to find my wife had basically bookshelfed the computer by piling a bunch of boxes on both sides of the computer almost completely sealing it from getting cool air.
Well, if your motherboard is an nforce4 chipset (which it most likely is), you can download nVidia's nMonitor (aka nTune), which will tell you both cpu temps and north bridge temps. Using nVidia's official software is much much easier than configuring the other programs, especially since I had major problems with getting MBM5 to report the correct temperatures. Also, MBM does NOT support most newer motherboards (they are not listed on the website with known settings).