I have an overheating issue here are my computer specs:

Sony VAIO PCV-RS 420
Intel Pentium 4 2.8 GHz
768 MB RAM
128 MB ATI Radeon 9500 Pro

Whenever I compile programs or play games on my Linux box, my computer overheats like mad. I started pulling off the cover of the box recently. I realized that my room's average temperature dropped by about 5 degrees (the price I have to pay to keep my computer from overheating like mad). However, I want to know if I can underclock my processor or my video card (the probable culprits) to see if the overheating will stop. Turning-off symmetric multiprocessing in my kernel kept the computer from overheating a while longer than if SMP was on. When I play games, within 2 minutes of the OpenGL initialization, my computer starts whizzing like mad with the fans running full blast. After about 20 mins-1 hour of playing, it freezes.

Basically I want to know how I can underclock my P4 or Radeon. Or if there is an alternative way to reducing heat (like a new driver or some kernel component). The overheating is really getting on my nerves because this never ever happens on my Windows partition.

Tried lowering the FSB in the BIOS (if possible)? That's the easy trick.

If this never happens while using Windows (which is strange to say the least), can you give any temperature readings from both while going at full speed?

I think I'm getting these readings right, but I'm not quite sure. These readings are for the chassis with the power supply and fan right next the temperature probe.

When playing Armagetron for 20mins with the Linux goes over 60 degs C
When playing Armagetron for 20mins with the Windows goes to just under 50 degs C

Armagetron isn't a reliable test. There are performance differences between the systems. Much depends on the graphic drivers.

Try cpu burn-in: http://users.bigpond.net.au/cpuburn/

How many fans are in your cabinet, and are they installed properly? In other words, the air flow should be in one direction -- if you have all your fans blowing inward for example you will not get the cooling efficiency that you would have if the front fans blow inward and the rear fans blow outward. Along those lines are there any objects that would block the airflow, such as having the PC in an enclosed space, or is the PC backed up against a wall? -- J.W.

I'm not sure about the temp limits on Pentiums, as I don't use them, but those temps don't seem terribly high. However, like J.W. mentioned, I'd suggest cooling your system down rather than slowing it down. Air flow is the important thing here. I typically have a fan or two in the front of my case pulling air in. Then a fan or two in the back, pulling air out. This allows cold air to enter the front of the case and force the hot air out the back.

One common problem I see in alot of cases is poor cable managment. Don't just slap those cables in and hang wherever. Try to organize them. Tuck them into empty IDE slots, tie them together, tape them down, and do whatever you can to keep them from blocking air flow. You don't need 10 fans in your system to keep it cool, just good air flow. You may also want to check your CPU's heatsink and fan.

I currently have a AMD64 3200+, 2 HD's, 2 CD-R's, a GeForce 6800, all creating heat and my CPU idles at 45C and jumps up to about 58C under full load. I'm only using 2 fans, one in the front and one in the back. My power supply also has two fans that pull air out, but that's standard on PSU's these days. The trick is that all my cables are tied up and run neatly.

*Edit*
I just realized where you said you have your temp probe. You system temp(air inside the case) should only be about 10-12C hotter than room temp. Then, assuming your CPU's heatsink is working correctly, that should only be 8-20C hotter than system temp, based on your CPU heatsink. If you're seeing temp increases more than those, you have room for improvement.

Thanks for the help... I'll work out the cooling system... may be I need to readjust a fan.

As a followup, in my experience, typical system temps usually range in the low to mid 40's C. Depending on the climate where you live and the particulars of your system, they can be higher or lower, but I'd say that once you get into the mid 50's C, your system would be considered to be running hot. If you're over 60 C (on a sustained basis, not a temporary spike), at least in my opinion you would definitely want to take action to keep that machine cooler. Good luck with it -- J.W.

My CPU was idling at around 65 C, which I found extremely distressing. I had two (fairly crappy) 80mm fans, one in front as intake and one in the rear as exhaust, and I decided I'd get more. I bought 4 Vantec Stealth 80mms and arranged it so I had three fans in the front as intake, two in the rear as exhaust, and one on the top as exhaust. Now my CPU idles at about 59 C. This seems way too hot for a 6 fan setup. Am I doing something horribly wrong?

One thing to note: my case has room for 13 fans: 4 in the front, 2 in the rear, 4 on one side, 2 on the other, and 1 on the top. I've been experimenting , but can't seem to get any decent temps. I also have rounded IDE cables, and most of my power cords are to the side of the case (although not really neatly, they're pretty much out of the way of airflow). Can one of you folks think of a better way to put 6 case fans in this situation? Or maybe have another solution for me, keeping in mind I'm a poor college student?

I underclocked my Athlon XP 1800+ (which usually runs at like 1.4ghz) to run at about 1.1 ghz. That brought the CPU temp down to the low 50's. It seems odd that to get normal temps I'd have to underclock. Could this be more than airflow? Should I look into a new heatsink/fan, &c.? I was under the impression that a non-overclocked system should be fine with the stock heatsink and fan setup.

The Best Advice is good airflow and good cable management. Also check that your heatsink is connected securely to the motherboard. I had problems which were caused by bad cables and my heatsink being a little to loose. I adjusted these and my system ran at around 40 degrees.

Didn't noticed this mentioned but case design is important also. I built a new system this spring and tried to reuse my old case. Which was sufficient for an AMD 2800+ & FX5700 but with my AMD 3500+ and 6800GT(could double as a space heater) not even close to adequate. I went from 5 x 80mm & 1 120mm fans in a standard ATX tower to 3 x 120mm in a server tower (Chenbro SR10769-BK) which made a huge difference in temps. Lesson here don't go cheap on a case.

old case:
Cpu idle @ 45-50c
Gpu idle @ 84-86c

under load I had graphic corruption within 10 minutes from the video card getting too hot

new case:

Cpu idles @ 34-36c
Gpu idles @ 56-58c

under load (Doom3 for an hour)
Cpu @ 39-42c
Gpu @ 64-66c

Most of the best points are already covered. My thoughts:

People have noticed that in some computer cases a purely one directional air flow is better. To DiscoStoo, this might mean that you could try taking the fan that is exhausting on top and move it to either the front or back. It might cause less turbulence in the flow. Also, double check to make sure all the fans are facing and blowing in the right direction. For other components, the material of the computer case is something to pay attention to. Some materials will conduct heat from inside to outside faster than others. Also, you'll probably want to make sure that the power supply has good air flow built in to it. An intake and exhaust built in to the power supply itself is sometimes helpful. Otherwise it could be venting excess heat into the rest of your case as its temperature goes up.

I was thinking about trying just that (moving the exhaust fan). I'm gonna give it a shot when I get back from work today. I was just afraid I'd have too much intake and not enough exhaust, but clearly whatever I'm doing now isn't working anyway. As far as my case goes, I think it's okay, it's a fairly large tower that's mostly empty, and although there's some slight wire clutter it could be a lot worse.

In my experience, I've never seen a need for a ton of fans. I'd say 4 fans max. Anything more then that, and you're just using up power. The one thing I would suggest, and doesn't cost a ton of money is a GOOD heatsink for your CPU. Yes, a stock CPU heatsink will work, but the manufacturer will also say that your chip is stable up to 85C. I dunno about you, but I don't want my CPU anywhere near 85C. If you do decide to upgrade your heatsink though, be very careful with the install. When applying thermal compound, it should be a very small amount; about the size of a BB. Here's a few newer heatsinks I'd recommend:
GH-PCU22-VG I'm currently using this on my AMD64 3200+. I have 1 intake fan, 1 fan pulling air out, and my power supply has 2 fans. I idle at 45c.
Hyper 48 This would also be a decent heatsink and fan combo.

These are just a couple examples. The newer heatsinks using the heat pipes can really drop your temps alot lower than a stock heatsink. The prices on most of these style of heatsinks is roughly $40-$50 here in the US and is worth the money. I don't run stock heatsinks on any of my systems.