Why does System Properties display two different frequencies?

5

My System Properties window has the below text (also see screenshot). What does the "1.20 GHz " refer to?

Hewlett-Packard
HP Compaq dc7700p Convertible
Intel(R) Core(TM)2 Duo CPU
E4400 @ 2.00GHz
1.20 GHz 3.50 GB of RAM
Physical Address Extension

alt text

AngryHacker

Posted 2010-06-11T22:33:09.627

Reputation: 14 731

Answers

5

Most modern Intel CPUs have SpeedStep, which means that the CPU will reduce its speed by lowering the multiplier and lower its voltage to conserve power when it is idle. Your CPU is currently running at 1.2GHz, but has a maximum frequency of 2.0GHz when under load.

MDMarra

Posted 2010-06-11T22:33:09.627

Reputation: 19 580

How do I kick up the speed to 2GHz - my box is not a laptop, so I see no reason to run at 1.2 GHz. – AngryHacker – 2010-06-11T23:15:44.780

1

Your CPU will automatically jump up to 2GHz when it's required - idling at a lower speed lowers the power requirement as well. If you still want to turn it off, set your Power Profile (Control Panel -> Power Options) to the "Always On" power scheme (instructions from Intel)

– Jared Harley – 2010-06-11T23:22:42.690

1@AngryHacker - You can disable SpeedStep if your BIOS supports it, but there's really no reason to. Once you do something on your computer that will require more computing power than that 1.2GHz can provide, your computer will automatically raise the speed. The point of SpeedStep is that most of the time, CPUs are not even close to being taxed. During that time the voltage+frequency is lowered so that it saves power and reduces heat to lengthen the life of your components. There's really no upside to disabling it. – MDMarra – 2010-06-11T23:23:01.143

@MarkM That's odd. I indeed switched to Always On and according to CPU-Z, the Core Speed cycles between 1191 and 1995 MHz (and the multiplier accordingly cycles between 6 and 10.

So it seems like switching to Always On actually enables switching CPU speed because when I had the power scheme set to Home/Office Desk, the speed never veered from 1.2 MHz. – AngryHacker – 2010-06-11T23:55:52.203

@AngryHacker - Those are just presets that can be changed. If you go to the advanced power management options you can specifically control min and max frequency. Someone may have been tinkering with your machine and changed the presets at some point. – MDMarra – 2010-06-12T00:11:42.727

@MarkM I do not see any button to go to the Advanced Power Options. It's neither on the Power Schemes nor Advanced tab. – AngryHacker – 2010-06-12T00:15:38.193

@AngryHacker - Sorry, those options aren't in the XP GUI, you have to use powercfg from the command line to set it. My mistake. It's been a while since I've used XP. – MDMarra – 2010-06-12T00:31:39.590

0

The second speed usually refers to the actual speed of the processor, while the first is the "Rated" speed that the processor is designed to run at. You see this most commonly if the processor is clocked down to save power when idle. It is being word-wrapped to the second line because of the width of the window.

Darth Android

Posted 2010-06-11T22:33:09.627

Reputation: 35 133

@MarkM yes, I did, until I looked more closely at the image >.> – Darth Android – 2010-06-11T23:06:47.453