Does SppedStep reduce bus speed too? X24 bus speed changes!

[underclocker]

Maybe this is normal, but I've never noticed it before. With my X24, and using the IBM MaxiMiser battery scheme utility, I set the CPU to very slow on battery power. With this scheme, the Pentium III-m 1.13GHz CPU (8.5 X 133MHz) clocks in at 733MHz (5.5 X 133MHz), which seems correct. However, sometimes while monitoring with both Mobilemeter and CPU-Z, I see the bus speed drop to around 115Mhz or 97.6MHz resulting in clock speeds that range from 533 to 666MHz. Is this normal behavior?

Everything seems fine, I just didn't realize that either SpeedStep alone, or somehow in conjunction with IBM utility programming, can modulate bus speeds.

Interesting.

[rkawakami]

By any chance are you running Windows 2000 on the X24? If so, when operating off of battery alone, I've seen a 600X's bus speed go from 100Mhz to 51Mhz with Win2K.

ref: http://forum.thinkpads.com/viewtopic.ph ... 470#174470

[underclocker]

Ray, at least I'm not alone. No, I'm running XP, but I don't think it's the OS doing the bus speed trimming. It also may not be as noticeable on XP, because there may be some XP processes that keep the bus speed up a little. For instance, when I open a new program the bus speed will increase to 733MHz from 533MHz. So I'm assuming that one of the 30 or so processes could have the same effect, which would explain why there is a fluctuation.

Back to the root of the question, I wonder if it's an IBM BIOS feature that is triggered by the battery utility? Or, is it part of the SpeedStep implementation designed by Intel?

It doesn't seem terribly consistent, though. Sometimes my machine will flat line at 733MHz and not dip below for a long time. But then again, maybe there is a process (like WiFi, for instance) keeping the CPU busy and at the scheme's upper CPU speed limit.

If all is working properly, it is pretty cool that both the CPU and FSB can be throttled.