Should a video card fan run constantly?

When playing games, I've had problems with hangups and reboots. The last time, I took the case off, cleaned things off and rebooted. I noticed the fan didn't start up and the card was a little warm. Should the fan on the card start as soon as power goes through the motherboard, or does it kick on at a certain temperature. Just wondering so I know whether I've got a dead fan/ video card, or if I just have to sit there and wait to see it kick on. Thanks!|||the fan should run all the time.........at least the nvidia's i deal with do........i have a 8800gt oced, and running the fan at 40% while not gaming........when gaming as the temp rises i have it set to run at 80%.........thats using riva tuner...........you can down load, riva tuner or atitool to see if your fan is operating and at what rpm.........or game with the side panel off, and reach in after a bout ten minutes, and put your hand under the card, ya should feel air getting sucked into it, or if ya dont do that you will atleast here it..........you can download everest 2.20 and monitor your temps also.........should be 50c idle and like 75c underload..........but that depends on the card ya got to............good luck......scott|||The fan on your video card should run continuously even when you are not playing game but the fan should run faster when you are playing game.