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I want to overclock my Desktop computer: Intel Core 2 Duo E6550. I googled it and I found many sites, but none for Linux (I have Ubuntu 8.10)

Can anyone help me to find out how to do that?

Overclocking under the BIOS seems to be impossible in my DELL comp, besides, DELL limit options in its BIOSes because they does give best performance already.

But, I would like to not Upgrade my CPU speed, but Downgrade it... if someone asks why, I just can say that I'm performing some Predictability/performance Benches, and I would like to run my 333MHz 4 bumped FSB at 100MHz 4 Bubmped FSB in order to check if when CPU speed is lower, performance goes lower either, but predictability increases as well...

a solution does exist: I just have to set the two MSR bits of the MSR_FSB_FREQ register to 100b (for binary) as suggests it the Intel Architecture manual Vol 3.B. The problem is that it seems to fail when I try to write on this register, and the most bizarre thing is that it is the only register that won't write...

This is why I'm asking about overclocking under Linux (I work with Linux), cause it seems to be not possible when I try doing it programatically... so maybe one of you knows some software or some trick to make it?

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should be a superuser question. – nkr1pt Oct 1 '09 at 13:25
moho, this is a question for ServerFault not StackOverflow. – psasik Oct 1 '09 at 13:26
Why you want to overclock your desktop? – voyager Oct 1 '09 at 13:28
Why would you not want to overclock your desktop? (Assuming you have good hardware and some tolerance for risk!) Intel's Core 2 architecture leaves plenty of overhead on lower-end CPU's, which are made of the same stuff as the higher end models. – kmarsh Oct 1 '09 at 17:34
@kmash: because depending on what you are overclocking, the possible stability hit is far higher than the performance improvement. Unless you do have a specific reason to overclock (you need better performance to run blender, for example), I wouldn't bother now. Even if I used to overclock for a long time, I found it to not always be worth the trouble. – voyager Dec 14 '09 at 6:36
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migrated from stackoverflow.com Oct 1 '09 at 13:28

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5 Answers

up vote 3 down vote

Overclocking CPUs is usually done via the motherboard bios software. You can get utilities in Windows that will overclock your CPU. But it is recomended that you do it through the BIOS instead.

In order to overclock your motherboard must support things like increasing the FSB speed as well as the CPU multiplier. Most standard motherboards do not support this. You need a slightly higher end motherboard to accommodate it.

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I agree with jjnguy's answer. It's best to do it through your BIOS. Visit your motherboard's web site and look through their manual to find out how to get to the BIOS and what options you have. I found a link on Ubuntu's forum though - you may want to give it a lookie-loo. http://ubuntuforums.org/showthread.php?t=707135

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Overclocked hardware leads to system instability. This is a general rule.

That's why as soon as you'll complain about stability issues in Linux on overclocked hardware, you'll simply get ignored.

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As a general rule, general rules should be ignored. Intel's lower-end E series are very good overclockers. I ran a similar one with a 50% overclock as my primary desktop for a year and a half, before buying a quad core once the prices came down. – kmarsh Oct 1 '09 at 17:36
Yeah, overclocking on Linux is sort of an oxymoron. Linux is best known for stability, overclocking sort of diminishes that. – John T Oct 1 '09 at 17:59
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up vote 0 down vote

If you have a major manufacturer's computer or very low-end (usually microATX) motherboard, with integrated video and a low-end chipset like G31, you may find your BIOS overclocking options either very limited or nonexistent. You will have better chances with a name-brand M/B (Asus, Gigabyte, MSI, etc) and a P43 or P45 chipset. Dual BIOS motherboards with automatic CMOS reset are preferred.

The e6550 will overclock, but it is not a great candidate for a really big overclock because it already has a 1333FSB (333MHzx4). Simple overclocks to 340MHz (1360FSB) or more are possible with good memory, much more than that and you'll have to either have premium RAM+higher RAM voltage, or change the FSB to memory ratio, which may impact performance.

If you are not willing to invest some time rebooting often and testing for stability (with smoething like prime95), don't bother. If you really want to learn a lot, give it a shot.

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You can, as others have pointed out, but does that 10% different matter when the OS scheduler is actually sane, and the rest of the windows don't freeze up when one actually crashes, etc etc?

Modern overclocks are marginal enough that it's not really worth the bother. When you overclock it to the point that it could make a difference, it's usually only stable enough for you to pop open CPU-Z and take a screenshot anyways. It mattered back in the day when a Celeron 300A went up to like 500. You hardly see that nowadays.

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