It is safe to disable SpeedStep to solve "speed of processor limited by system firmware" problem?

Good morning.

I purchased a Latitude E5530 machine(although I believe my problem applies to other machines as well) and when on battery(not when on power), I was having four event viewer warnings as below:

"The speed of processor n in group x is being limited by system firmware. The processor has been in this reduced performance state for y seconds since the last report."

This is a brand new machine on which I installed Windows 7 myself and all Dell drivers in the correct order after downloading them from dell.com after supplying my service code. As a result of the latter, I have no yellow exclamation marks in Device Manager.

No overclocking done.

I also applied Service Pack 1 and updated Windows via Windows Update. No software is installed at the moment except Kaspersky Internet Security.

To solve the issue, I first tried to set "Minimum processor state" under "Processor power management" in the advanced options of my power profile to 100% for "On Battery" but after a reboot, the problem was still there.

I then disabled SpeedStep in BIOS and the problem went away. What also went away are the "Minimum processor state" and "Maximum processor state", in Windows, under Power Options.

My question is: Shall I leave SpeedStep disabled? I read online that those event viewer entries could mean a hardware fault but if this was the case I would experience the same when on power, no?

As a final note, after I rebooted with SpeedStep off, battery remaining time(that was 3h30m before reboot) was still like that after reboot whilst CPU utilisation was normal as well (0-2%) after all services and startup applications loaded, hence no unusual CPU fluctuation that could indicate overheating.

20/08 Updated: Update in order not to bump the thread. With SpeedStep disabled the machine has been running fine for months, including applications like Visual Studio.

Thank you.

 

I could be wrong about this, but at least in older Intel CPUs when you disabled SpeedStep the CPU would run at it's lowest clock speed. You should be able to check the clock speed using CPU-z or similar program.

By the way, did this event viewer warning coincide with any actual decrease in performance?

 

Thank you for the reply namaiki.

Unfortunately I cannot answer that yet since I don't have anything installed on the machine yet.

What I can say is that boot-wise, there's no difference between on power and on battery, it takes the same amount of seconds(more or less, of course).

Also, the warnings started from the first time I used the machine on battery, which was yesterday, after I updated Windows. Before that(installation, drivers, SP1, etc.), it was always on power.

 

I've just installed CPU-Z to benchmark CPU performance, comparing CPU Speed when SpeedStep is disabled (vs enabled) re Event Viewer Warning #37.

enabled (browsing, otherwise OS is "load-free" - CPU spikes @ 20-30% whenever taskmgr.exe is spawned, then almost instantly drops to 1%



rebooting to compare....

 

identical results! (although it took a while for CPU-Z to load).

 

It might be informative to run HWiNfo which has a nice dynamic CPU speed display while the Sensors window includes estimated CPU power drain.

John