[AlexN]

Macworld has done a test on apps performance on both Core Duo and Core Duo with one core disabled, but no mention on how to do that.
Does anyone know how do I temperarily disable the other core?

[hotch]

step one: install x-code

step two: i'll let you know when mine gets here friday

[SpecMode]

Install the XCode developer tools from the Restore DVD, like hotch said. When you're done with that, open System Preferences; you should see a 'Processors' icon under the Hardware section. Open that, and you should see the option to disable the second core (just uncheck CPU2 or select '1' in the 'Processors:' droplist).

[AlexN]

Originally Posted by SpecMode Install the XCode developer tools from the Restore DVD, like hotch said. When you're done with that, open System Preferences; you should see a 'Processors' icon under the Hardware section. Open that, and you should see the option to disable the second core (just uncheck CPU2 or select '1' in the 'Processors:' droplist).

I have installed XCode, but I don't see "Processors" in System Preference.

[Wickers]

I'm just wondering, why are you interested in turning one core off?

I mean, a core solo would have saved you a few bucks and got the job done effectively.

[jbsengineer]

plus having 1 core turned off will chew your battery life up x 2...

[Mr Beardsley]

I have installed XCode, but I don't see "Processors" in System Preference.

Make sure you install the CHUD tools.

[Dorian Gray]

Yes, switching off one core would probably reduce your battery life. Is there a practical reason for doing this?

[Wyatt]

Originally Posted by Dorian Gray Yes, switching off one core would probably reduce your battery life. Is there a practical reason for doing this?

I can only think of one "practical" reason, and that's testing apps you've developed on single-core systems to see how they'd perform without having to buy another Mac just for testing. Other than that, I can only think of pure curiosity.

[hotch]

apparently it improves battery life tremendously... but i haven't seen any solid tests yet

core solo would be perfect for watching a flick on an airplane...

[jbsengineer]

Originally Posted by hotch apparently it improves battery life tremendously... but i haven't seen any solid tests yet core solo would be perfect for watching a flick on an airplane...

from what I've read and heard the core duo is designed to only operate as a core duo. thus shutting down 1 core will exhaust the remaining core and reducing battery life significantly. someone in another forum shut one down and immediately saw the battery life meter go way down.

[Dorian Gray]

You can be pretty sure it won't improve the battery life, nevermind "tremendously" improve it: otherwise Apple/Intel would have implemented such a feature as a power saving feature. Common sense suggests it would increase power consumption anyway, at least if the computer is actually doing anything (such as watching a film). The power/performance curve for a CPU is exponential: to do twice the work requires [much] more than twice the power. Therefore it stands to reason that sharing the work between two cores, thereby allowing each of them to operate at a lower power level, would reduce overall power consumption.

The obvious exception would be when operating at 100% power, such as encoding a video. With one core shut down the power consumption would be a lot lower, but the time required to complete the task would nearly double.

[hotch]

do we know if rosetta utilizes both cores?

[bassplayinMacFiend]

Originally Posted by hotch step one: install x-code step two: i'll let you know when mine gets here friday

step three: Profit!

[Dave]

Originally Posted by hotch do we know if rosetta utilizes both cores?

I can almost guarantee it. (Based on my speculation regarding its performance, not any actual evidence.)

[AlexN]

Originally Posted by Mr Beardsley Make sure you install the CHUD tools.

Got it. Thanks.

Yes, shutting down the other is just for testing purpose only. I love this dual-core Core Duo.

[WrestleEwe]

There was an option in the cpu-meter of BeOS (remember that?) to turn processors on and off.

Guess what the developers forgot to put in version one of that app.
Guess what happened to your system when you turned both processors off...

anyway.. back to the topic

[turbulentfurball]

You're kidding!

I think that's a case of all brains, no common sense.

[MrENGLISH™]

Originally Posted by WrestleEwe There was an option in the cpu-meter of BeOS (remember that?) to turn processors on and off. Guess what the developers forgot to put in version one of that app. Guess what happened to your system when you turned both processors off...

Anyone stupid enough to turn off BOTH processors deserves the outcome.

[Schnauzer]

Originally Posted by Davimation Anyone stupid enough to turn off BOTH processors deserves the outcome.

LMAO!!!!!

[Robo]

(This is text I'm adding so that the Ds in the smileys don't get de-capitalized by an all-caps filter, thus turning my smileys into ":d"s.)

[hotch]

Originally Posted by bassplayinMacFiend step three: Profit!

o rly?

[hotch]

anyway, my MBP is on the truck for delivery right now... i'll test this multiprocessoritude tonight.

[fisha]

if anyone has the mini core solo, can they try enabling the second core of the mini using the reverse of the method described here to diable a core?



Since it seems that the Core Solo mini is reporting itself as a core duo processor, its got to be worth a try to enable that second core?

[ZachPruckowski]

I heard that some of the Core Solos were Duos with a defective core or just a really slow core disabled by Intel. So fisha's idea could either work great (if it's just a slow one), or, well, screw up your computer (if you are running on a defective core), as I understand it.

[Dorian Gray]

The redundant core will have been disabled by Intel at the hardware level long before they reach Apple.

[fisha]

any thoughts on how they would do that?


and secondly, if its off the same production line, then surely they are 1.67Ghz models. what and how would they change them to 1.5GHz?

[Wickers]

Sounds like you need to look into the basics of computer hardware, and the relationship between the the FSB and CPU clock speed.

[Dorian Gray]

The CPU operates at a frequency determined by the product of the front side bus speed and a clock multiplier. So in the case of the Core Solo Mac mini which has a 667 MHz front side bus, a clock multiplier of 2.25 would be used to make the CPU operate at 1.5 GHz. On the Core Duo, which also has a front side bus clocked at 667 MHz, a different clock multiplier of 2.5 would be used. CPUs don't have an inherent frequency at which they operate, although they do have an upper limit determined by a huge variety of factors including the process used, chip architecture including pipeline length, superscalar implementation, environmental temperature, and to a certain extent, luck on the manufacturing line.

(The front side bus, in case you're unfamiliar with the term, is the data bus over which the CPU communicates with the RAM and other subsystems.)

So the "1.5 GHz" Core Solo chips may well be capable of operating at a slightly higher frequency with good stability, but Apple chose to clock them at 1.5 GHz. If in fact the Core Solo is a Core Duo with one half disabled, it is likely that Intel is salvaging chips which have manufacturing errors in one core. The manufacturing process doesn't deliver 100% yields, so a significant proportion of dual-core chips manufactured will have problems in one of the cores but not the other. These would have to be thrown out if Intel couldn't sell them (at reduced prices of course) to companies like Apple.

[chucker]

Actually, I'm quite sure quad-pumping does not affect the multiplier at all. Therefore, the multipliers you cited would actually be a lot higher: of all current Core Solo/Duo CPUs used by Apple, the "true" FSB speed is 167 MHz. So you have 9 for the 1.5 GHz Mac mini Core Solo, 10 for the 1.67 GHz Mac mini Core Duo, 11 for 1.83 GHz iMacs and MacBook Pros, 12 for 2 GHz iMacs and MacBook Pros and finally 13 for the 2.13 GHz MacBook Pro built-to-order option.

By your logic, i.e. a multiplier based on the 667 MHz quad-pumping, you'd have a Mac mini Core Solo multiplier of 2.25, something that obviously doesn't quite work.