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Old 11-25-2001, 12:19 PM   #1
Jimbo Mahoney
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Overclocking


I am an experienced overclocker (in a windows environment), but what does Linux do when it is overclocked (too far)?

Reason I ask:

The cellies in my sig both run @ 550 under a Windows environment.

The box as it stands is running with 100% CPU usage 24/7 (Folding@Home) with both CPUs @ 506, 2.05 volts (2 volts default). No APIC errors.

More volts gives APIC errors (are they bad?)

What is the worst that could happen if I push the CPUs up with no more voltage (I think they need 2.2 to run @ 550)?

Will the filesystem eventually become degraded and require a reinstall?

Thanks,

Jimbo
 
Old 11-25-2001, 07:20 PM   #2
Jimbo Mahoney
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Hmm.

Not a lot of Overclockers here huh?

I found out about APIC -

Advanced Programmable Interrupt Controller

But (out of ten) how bad are APIC errors?

Do they just delay something getting done?

Will the process repeat until it gets through?

So APIC errors slow a system down, nothing more?
 
Old 11-25-2001, 07:35 PM   #3
Jimbo Mahoney
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Well, in 3 days, 7 hours and 29 minutes, I have had 14 APIC errors.

I don't think that's too bad.

Will gradually overclock a bit more and check the regularity of these errors.

Regards,

Jimbo
 
Old 11-25-2001, 07:35 PM   #4
DavidPhillips
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Your CPU is gonna melt

Do you have the proper cooling to supprot the voltage you are using?


There is a good program you need to use. It is lmsensors or sensors.


It came with my distro, is easy to install, and will tell you your system voltages, Temperatures and fan speeds.


If you have problems getting it working let us know here...


There is a cool applet for the panel also that works with it.
 
Old 11-25-2001, 08:35 PM   #5
Jimbo Mahoney
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Yes I think I might have the cooling to deal with the CPUs

Default wattage of celeron 366 = 21.7 watts.

Therefore a celeron 366 @ 550 and 2.2 volts gives out:

( 550 / 366 ) x ( 2.2 / 2 )^2 = 1.818

1.818 x 21.7 = 39.5 watts.

Both processors are lapped to a mirror finish to the copper.

Both heatsinks (FOP 32s) are also lapped to a mirror finish.

A minimal amount of Arctic Silver II is used as the thermal interface.

The thermal resistance of a FOP 32 (not lapped) is approx. 0.6 'C/Watt. (Although both fans are running at 7 volts to save my ears.)

Thus (assuming an ambient temperature of 22 degrees Cel. gives the temperature of each processor core (at full load) :

( 0.6 x 39.5 ) + 22 = 45.7 'C

This is well within Intel spec.

Both processors are reported as being at 39 'C in BIOS immediately after a reboot where they have been running 100% load. (This is when they are @ 506 Mhz, 2.05 volts). However the motherboard socket probes are never to be trusted, hence my therma probes in my main Athlon rig).

In addition, I have two 80mm Evercool Intake fans, each pushing 29 cfm of air into the case.

I have run each processor at 2.6 volts to see how far each would clock with no thermal problems.

Remember that a FOP 32 is capable of removing approx. 60 watts of heat. A FOP 38 is capable of up to 80 watts.

My watercooled Athlon system has to cope with 111 Watts of Heat in an area approx. 1cm sqaure!

Currently testing both celerons at 5.5 x 98 (539 Mhz) to give a total of 1.078 GHz

Nice.

Will report back on rate of APIC errors and any unusual symptoms.

Regards,

Jimbo
 
Old 11-25-2001, 09:33 PM   #6
rolf
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Reading some of the posts on fa.linux.kernel, I get the impression that the folks who develop the kernel view overclocking as creating unnecessary risk of introducing error. In other words, they don't want to hear about bugs from anybody who overclocks. Guess it depends on what's important to you.
 
Old 11-25-2001, 11:36 PM   #7
mcleodnine
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You said that your Celerons and your heatsinks are lapped to a mirror finish, but are they _flat_? If you know someone who works in a machine shop or can talk nice to a local shop, you get them to check how flat they are (or not) with a set of optical flats. They're optical glass with a high index of refracition which will show alternating bands under a light source - straight bands == good, curved or arced bands == bad.

As far as corrupted filesystems go, I've seen it happen in Winders and Linux. Bad things happened to a client's fat32 when their fan siezed completely on an O/C'd P200.

D_Phillips: You've had some success with lmsensors - congrats! It gave me enough grief on my Intel i815 and ABIT boards that I finally gave up. I'll try again...
 
Old 11-26-2001, 04:46 AM   #8
Jimbo Mahoney
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Yeh, they are flat. I sanded them down specifically on a piece of glass using wet/dry upto 1500 grit. They are a whole load flatter than non-lapped. (When I lap my CPUs / heatsinks, they almost always start to become warn at the edges, suggesting they are concave )

So overclocking isn't a Linux 'thang' huh?


In 8 hours, 39 minutes I have had 2 APIC errors. This is with both CPUs @ 539 Mhz, 2.1 volts.
 
Old 11-26-2001, 06:26 AM   #9
cornet
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Jimbo: Ignore the APIC errors, unless you get 1000000's then they ain't gonna slow you down.

I run a BP6 as well but with celey 400's @ 570 (will go to 600). The BP6 is known for producing these errors, there is nothing to worry about, (the BP6 is a blatent hack and there are inherent problems with it)

Whats the worst that can happen ?
Look at it like this 1 ACPI error = 1 instruction has had to be processed again.. um how many millions of instructions can your CPU's carry out per second

Hope that sets you mind to rest!

ACPI errors will occur in windows too but windows doesn't report them.

Get em back to 550 and quit worrying..

cornet
 
Old 11-26-2001, 06:35 AM   #10
DavidPhillips
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Well Jimbo It sounds like they ought to be staying cool in there. LOL



I fought with lmsensors for a while until I figured out it was the i2c-isa driver that made it work. It works great now, I have it tweeked to read the same as the bios.

This is on a MSI K7-T Pro 2-A.

I got it building a little web page with the info so I can check it from anywhere.

Last edited by DavidPhillips; 11-26-2001 at 06:36 AM.
 
Old 11-26-2001, 08:48 AM   #11
Jimbo Mahoney
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Cheers guys (espesh cornet - your first post!)

Will clock 'em up soon
 
Old 11-26-2001, 09:48 AM   #12
Jimbo Mahoney
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Back to 550 each now.

Totalling 1.1 GHz in an SMP Linux Box.

Nice.
 
Old 11-26-2001, 02:29 PM   #13
Jimbo Mahoney
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er, cornet, is 202 APIC errors in 4 hours 45 minutes too many

hehe

Good old overclocking
 
Old 11-27-2001, 06:57 AM   #14
Aussie
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I run my 1gig T-bird at 1333...great for compiling kernels
 
  


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