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On my gaming desktop, I was fixing my desktop's power supply when something seemed to burn (I got that stinging burning smell). However when I turned ON the computer (it was OFF before), everything seemed to be fine.

However, I have noticed that now it becomes too slow if I play a game or movie on it. I am talking about the computer becoming painfully slow after about 5 minutes into the movie/game (it works fine otherwise e.g. browsing), it becomes so slow I can see individual frames from movies/games.

What could be the problem? A fried video card? friend memory (RAM), something else?

My system's configuration is:

HOW I FIXED IT: Credit to the excellent answer below (the one that's accepted), my problem was a faulty fan for the video card, video card was over-heating and hence the slowness. My video card wasn't very good anyway, so I replaced it with a better one and the problem was resolved.

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Check the temperatures of your system (SpeedFan is a good program for this). It sounds like your system is getting hot from all the work and the CPU is getting throttled to cool it down. When this happens, try quitting the game or movie and letting it idle for a while then see if it the game runs fast again for a while. –  Synetech Jul 5 '12 at 20:38
    
you are right, even before checking temperature, I knew that if I let it sit idle for some time, it starts to run fast again (for a while). I installed SpeedFan. things started to slow down once my CPU temperature went to 58C and GPU temp went to 110C (my GPU is running at 87C even now when it's been idle for sometime, could this be the issue?) –  ishaq Jul 5 '12 at 21:25
    
i am almost sure it's my GPU fan, I tried again, as soon as it hits 110C, things start to slow down noticeably. any suggestions on whether my diagnosis is correct and what should my next step be? –  ishaq Jul 5 '12 at 21:32
    
Yeah, that sounds like the problem. According to NVIDIA the max temp for that model is 105 C. –  imtheman Jul 5 '12 at 21:33
    
yup, you are right, I am about to take it out and have a look. –  ishaq Jul 5 '12 at 21:43

1 Answer 1

up vote 2 down vote accepted

Whenever you find that a computer runs fine for a while but then slows down after things like gaming, the problem is usually due to overheating.

Gaming is computationally expensive, so the CPU will heat up after a while. To prevent damage, most motherboards implement one or more thermal management systems to cool the CPU down. One common method is to inject a certain number of HALT (do-nothing) instructions into the CPU's buffer when it reaches a certain temperature so that the CPU has a chance to cool down.

One option is to adjust the temperature threshold and CPU throttling percentage in the BIOS, but the defaults are usually fine (in fact usually not enabled at all).

Video cards are also prone to overheating. They don't usually have throttling implemented at the motherboard level, but rather internally, so you don't usually have direct access to thermal-management.

A better solution is to reduce the heat generation in the first place. Here's a few tips to do this:

  • Adjust the internal components of the computer to maximize airflow inside the case
    • Use rounded cables instead of ribbon cables
    • Space out adapter cards
  • Make sure that the heatsink and fan are properly affixed to the CPU with thermal paste or pad
  • Place the system in the open air instead of in a closed closet
  • Ensure that there are at least one or two fans (that work of course) in the system (I asked about optimal placement and direction here)
    • Use water-cooling if money allows/is needed
  • Clean fans of dust and oil them
  • Make sure there is plenty of space around the video card(s) and that you are not recycling hot-air back in
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okay, so I removed the fan and heat-sink from GPU, applied a fresh coating of thermal paste, now it reaches 110C in about 25 minutes (as compared to 5 minutes before). The desktop is in a well ventilated area (almost in the middle of an air conditioned room), did I apply too much thermal paste? (I applied all there was in the package, about the size of a small pea). I can't see what RPM my GPU fan is running so don't know if fan is the problem, it is running however (I can see it). The GPU runs at about 75C for normal browsing. any ideas? Thanks for all your help. –  ishaq Jul 6 '12 at 13:41
    
am positive it's my fan, I just took a closer look at it and it seems to be running slow. –  ishaq Jul 6 '12 at 13:51
    
> did I apply too much thermal paste? It's possible. Like all things, too much of a good thing can be bad. While a thin layer of thermal grease helps conduct the heat from the chip to the heatsink, too much of it will actually hinder heat transfer. The standard method is to put as much as a small grain of rice, then spread it very thin with something like a credit card. > I can't see what RPM my GPU fan is running You can use ATI Tray Tools, Riva Tuner, SpeedFan, or other programs depending on what make and model the card is. –  Synetech Jul 6 '12 at 15:39
    
> it's my fan, I just took a closer look at it and it seems to be running slow Does it speed up or slow down at all? Check your video-card's driver software to see if there is a fan-speed setting; it may be set wrong and not speeding up as necessary. If it is not a software issue, then clean the dust. If that doesn't help, you may need to oil it. I wrote a good article on computer fan maintenance somewhere or other, but I don't remember where. Until I can find it, check out this good article by Dan's Data on the subject; it covers the same material. –  Synetech Jul 6 '12 at 15:46
    
oiling the fan, applying lesser thermal grease a second time has alleviated the problem (it still goes to the 90s temps but I guess it's just a crappy 3D card). Thank you for all the help –  ishaq Jul 7 '12 at 16:30

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