Underclocking for a Quiet Machine?

The Fun Guy writes "I'm running a PIII 600MHz, which I'm thinking of upgrading. If I could get rid of the fan and run more quietly, I'd love to. I run office-type apps, so I don't need the fastest processor around, but I also run d.net, so I'm constantly pegged at 100% usage. Aside from the obvious fact that your CPU is running slower than the listed speed, is there any downside to buying, say, a 1.8GHz chip and running it at 900MHz without the fan? Any experience or FAQ's to share on this?" We've covered this topic several times before, with some good feedback, however most of the approaches don't discuss the use of underclocking to accomplish this, although one common suggestion from the comments is to use a non-Intel processor, if you can. Have any of you tried underclocking your CPU to allow it to run silently? How far do you need to underclock a processor in order to enable it to run without a fan?

Comments

Informative?? Not...!

[itwerx]

A 1.8GHz processor running at 900MHz is going to let off as much heat as a processor in the same family rated at 900MHz...

Umm, yeah, right, you don't know much about CPU design these days do you?

Discounting the above, my own real world experience has been that Intel CPU's can typically eliminate the fan with a 20-30% underclock. AMD is almost not worth it needing at least 50% underclock. Also you NEED the biggest darn heatsink you can find and I strongly recommend active heat monitoring and some sort of automatic powersaving idle/shutdown/whatever if you leave the machine alone for long periods. Somebody mentioned large heat-sinks being close to the power-supply fan intake, this is a good idea and can be accomplished by using a duct (and possibly some judicious cutting) if your power supply vents are inconveniently situated.

easier way...

[Polo]

Here are the things you'll have to deal with when trying to quiet your system:

• cpu fan
  
• disk drive
  
• case fan
  
• video card fan
  
• power supply fan
  
• cd spinning

Ok, so my way of solving the problem doesn't involve underclocking, but it works better:

I put the computer in another room.

Get a good monitor cable (one with ferrite cores) and a keyboard extension cable and run them through a wall to the computer in another room. Now *that* is quiet. And it costs maybe $50.

Now to be honest, that's not exactly my setup. I actually have a KVM switch and hook to several computers in the next room. I have a nice quiet bedroom with a keyboard, monitor, speakers and a usb KVM switch. If you look at http://www.belkin.com you'll find kvm switches that switch audio too.

Redundant

[Perdo]

I have an 1800xp underclocked from 11.5*133 @ 1533mhz to 7.5*133 @ 1000mhz. With an MC462 heatsink and a tube fixed to the heatsink an exiting the top of the case and no fan, the CPU never exceeds 32 degrees celsius. The real test is to see how far you can drop the CPU voltage before instability arises. Mine is running at 1.65. Lower voltage plus lower frequency means less heat but remember I am using one of the highest rated heatsinks available. At 789 grams, this heatsink weighs almost 300 grams more than any other heatsink you can buy.

And yes, the chimney effect of the tube makes it feel like there is a fan blowing hot air, just like the G4 cube.