Nvidia Card Stops and Screen Freezes

Thank you so much! I am doing what you have recommended. I opened up the system yesterday and dusted it well, reinstalled the card and put a fan outside of the unit as it seemed to be very warm. The internal fan is working as well. I appreciate your help!

Hello again,
I am still experiencing the same problem. At random, the system freezes when I am either typing an email, playing solitaire or surfing the web. Sometimes, the screen goes black and sometimes it just stops with two or three vertical colored lines where the pointer is positioned. There is no activity on the hard drive light and the only way I can regain the system is to power it off and then back on. I checked the event viewer and the critical error is kernal-power ID 41 which I believe is related to turning the system off without the shutting down properly due to the freeze. Any suggestions or solutions? Thanks in advance!

Thanks so much for the additional information! I just opened the system back up and reseated the graphics card as well as USB card which sits right next to it. When the system came back up, there was activity in the system tray saying that a USB input device was installed correctly and almost immediately the system froze again. I took the SUB card back and took off the information which is a VIA VT6212L and is a 4 port USB card. I had received a message earlier in the week that a driver could not be found for the card and I am wondering if this is the culprit of the system freezing. There is nothing plugged into the USB card so it doesn't really make any sense, other than the system froze as soon as it found the card. Will it hurt the system to take the USB card out, I don't use it anyway. Also the fan is working and blowing out some air and I can feel some air by the power supply but not much, is it supposed to blow into the power supply or out? Thanks again! BTW - I look the seal picture with the flippers comment!

I still haven't resolved the issue, but I do have additional information that I hope will isolate the problem. I downloaded SpeedFan and it is reading the GPU temperature between 65 - 112 degrees within a very short time frame (5 minutes) within system coming on. I have a 305 watt power supply and asus.com says my system needs 400 watts, yet the system has been working off of the 305 supply for almost a year. Graphics cards going out or power supply? I truly appreciate your assistance. I was on hold with Dell tech support this past Friday for 2 HOURS with no assistance. My cordless phone battery went out before they picked up!