Pentium-M downgrading speed?

[RyanPaulShaffer]

Hello all. I finally got my Inspiron 6000, and after too much drama with Dell for me to recount here, I shall be keeping it. Anyway, I have a Pentium-M 750 running at 1.86 Ghz. Sometimes, however, I've noticed that My Computer and CPU-Z report it at 800 Mhz. I've heard that this is a power-saving feature of the Pentium-M, to downgrade the processor speed when it's not needed, but I don't understand why it keeps happening when I have the computer plugged in to AC power and set with the Dell Power Manager to Maximum Performance. Is there any way to control this in Windows/BIOS, or do I need a 3rd party program? Any help would be appreciated, as I don't really want my computer downclocking when I'm at my desk. Thanks!

Ryan

PS - I also noticed something weird when I run CPU-Z. I have a Pentium M 750 running on the 915 chipset. That's Sonoma, right? Because CPU-Z reports it as Dothan. Just curious...

 

[fbrdphreak]

First thing's first

Sonoma = entire Centrino platform, consisting of Dothan CPU, Alviso chipset (915), and 2200/2915 WiFi

Dothan = Pentium M CPU with 2MB L2 Cache, independent of FSB

I don't know why Dell's settings don't allow it to run at full speed, but let me stress that you don't need or really want it to run at full speed 24/7. Running at the full 1.86GHz, a P-M generates a lot more heat than when left set on Adaptive. The performance difference is a matter of microseconds (literally) and most apps don't notice. I do know that some coding applications I have used interacted slower when set on Adaptive, but other than that I've had no issues.

But you can download SpeedswitchXP to control your CPU's throttling on DC & AC.

 

[RobsTV]

Yep, SpeedswitchXP will fix you up.

To solve the temperature increase you may see when running at max 100%, install centrino hardware control. You can then lower your vcore as well as set temps that fans turn on or off. Most have no problem running P-M at 1.1v (check using stress tests like Prime95). Running at max speed here, 1.8Ghz at 1.1v, and my CPU and GPU fan only turn on when gaming. At max speed and 1.1v, temps stay under 52c with normal use and no fans. When on DC power, using max battery saving mode, CPU drops to 600MHz, and I've set vcore for 0.6v. Again, fans never turn on, which helps battery get close to 6 hours now.

 

[RyanPaulShaffer]

Ahhh...okay, thanks for the clarafication. So, the CPU will only downclock to 800 mhz when nothing much is going on, and then speed up to 1.86 Ghz when it needs to, right? Or is it always at 800 mhz? The reason I was concerned is that I did not want the CPU to always be sitting at 800 mhz, especially when I'm plugged it an my desk. I bought a 1.86 Ghz, dang it!

 

[corkyg]

Yeah - butit will stay cooler that way.

 

[vegetation]

Originally posted by: RyanPaulShaffer
Ahhh...okay, thanks for the clarafication. So, the CPU will only downclock to 800 mhz when nothing much is going on, and then speed up to 1.86 Ghz when it needs to, right? Or is it always at 800 mhz? The reason I was concerned is that I did not want the CPU to always be sitting at 800 mhz, especially when I'm plugged it an my desk. I bought a 1.86 Ghz, dang it!

Pentium M uses advanced power managment features that are transparent to the user. Heck, that's a major reason why Apple is going to Intel.

 

[RobsTV]

Originally posted by: corkyg
Yeah - butit will stay cooler that way.

Cooling is really a non-issue with the P-M.
As far as I know, it is the first CPU that can actually run 2Ghz + with no fans.
Don't worry about temps.
When at 100% it is still much cooler than any other non P-M running at reduced speeds.
Many owners of the i6000 are ordering it with the 100 MHz fsb 1.6Ghz CPU, then adding jumper wire to socket so it runs at 133MHz fsb, which ends up with the system running at 2.1GHz, all with stock cooling. Point is, stock P-M CPU's are worry free as to temps.

http://www.madshrimps.be/?action=getarticle&number=5&artpage=1155&articID=289

The only time you want to run at slower speeds is when using battery power.

 

[bacillus]

Additionally, if you want to extend your battery life per full charge you can consider undervolting your CPU.