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Sandy Bridge Turbo boost and thermals - notes from the field

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Summary

Lenovo is making headway with power management, thermals and the reduction of fan noise with the ThinkPad W520.  With the latest BIOS you can expect processing power on demand, efficient cooling, and a quiet machine at idle.

thinkpad-w520-3Overview

It’s hotter than hell here in Texas but that doesn’t mean the inside of your laptop has to be. We’re at the 25th consecutive day above 100 here Dallas so I decided to avoid the outdoor heat today, sleep late, and then do some investigative work.  The primary chore today was working with some video, but I took the opportunity to test some performance settings as well. As a result of the testing, I have altered my power management settings to take into account my findings. 

Configuration Tested

Today’s test included the Lenovo ThinkPad W520 with the Intel Core i7-2720QM processor. This is the MSIT standard configuration with some modifications.  I use the Intel Series 510 120GB SSD drive as the primary drive, have a secondary 80GB mSATA SSD drive, and in the Ultrabay there is a 750GB Seagate Momentus 7200rpm drive.  The Optimus video driver (v8.17.12.6871), power management driver (v1.62) and ThinkVantage Power Manager (v3.61) are the latest from support.lenovo.com. I am using a CTP version of the W520 BIOS and it is v1.26.  All testing was performed with the BIOS display mode set to Discrete.

BIOS Notes

The BIOS I am using is not yet on the support download area.  Some of the Lenovo community staffers made it available via the forums at https://forums.lenovo.com/.  I normally don’t install a new BIOS unless there’s a compelling reason.  I got interested in 1.26 because I was seeing some traffic that Lenovo had finally addressed some issues with fan speed and noise.  I was also seeing some posts I couldn’t really believe so I decided to do some testing of my own.

I downloaded the .ISO and burned the image.  By installing this BIOS I moved from 1.22 to 1.26.  The impact of the change was apparent right away. The machine runs noticeably quieter. In order to understand why, you really need some tools to help you see what is going on.

Utilities

HWiNFO32 is a great little tool that displays all sorts of wonderful information about your machine.  It will tell you the temperatures of the various sensors in the silicon, fan rpm, CPU core clock speeds, etc.  In short, it will give you a very good idea of what happens when you make adjustments.

Another utility heavily used by the ThinkPad community is the TPFanControl application.  This allows you to override what the BIOS and Power Manager settings.  I personally think this is a very dangerous practice and based on my testing today don’t think it’s really going to be necessary for the W520. If you decide to experiment, watch the temps carefully and don’t do anything stupid.  Burning silicon doesn’t smell good.

ThinkVantage Power Manager

As I recall from the last corporate MSIT image install I did, this powerful utility wasn’t installed.  I’m not sure if that was a bug in the MSIT install or by design.  I used to believe that Windows 7 inbox power management were good enough.  They really aren’t when you have good OEM tools to add value. ThinkVantage Power Manager is one of the extras I have grown to like. You really do need to make sure you are running the latest power management driver (v1.62) and the latest version of Power Manager (v3.61).

Attached you’ll find my custom power profile created with Power Manager.  You can easily import this without hurting anything.  Unless you are old school and really like reading .INI files, it’s much easier to review using Power Manager. Hint.  The profile is designed to optimize the W520 for battery conservation when off AC, or to provide maximum performance when plugged into the wall.

You will find very little documentation on Power Manager and the effect of the settings it uses.  I haven’t fully explored all of them yet but here’s what I did discover about some of the most important settings.

Power Manager | Basic mode | Power Use tab

  • Turbo Boost Plus – this setting is placed oddly on the Basic menu panels of Power Manager.  Turning this on kicks the fan rpm to 3800+ and runs all four cores at 3000 MHz constantly.  This mode is not needed unless you intend some long running CPU/GPU intensive jobs.  If that’s the case, it is required because this is the only way to kick the fan to the highest possible rpm for maximum cooling.

Power Manager | Advanced mode | Power Plan tab | System settings | System performance

  • Maximum Turbo – Runs the CPU cores at 3000 MHz constantly.  The difference between this setting and Turbo+ is that the fan doesn’t immediately kick up to 3800rpm.  In fact, the max possible fan speed is 3300rpm when using this setting.  The fan speed with increase under load as the temp rises.  The maximum temp observed with this setting was 87C (188F).
  • Turbo – runs the CPU cores at 800 MHz but will turbo them up to 3000 MHz depending on demand.  The fan speed will range from 1850 to 3300 depending on the system load and temp.  This is the setting you should use the majority of the time as it is the most flexible and efficient. The typical temp at idle is
  • Balanced – this setting is similar to Turbo but throttles the CPU cores to a max clock speed of 2200 MHz.  The fan range is the same as Turbo. 

Battery Power Reduces Clock Speed

If you boot the W520 on battery power, the max CPU clock speed will be 1500 MHz.  The same is true if you pull the power cord from the back of the W520 under heavy load.  Intel SpeedStep will step the clock down from 3000 MHz to 1500.  This happens regardless of the BIOS and Power Manager settings. 

Lowering the clock speed is understandable on battery power.  You can eat up a 9 cell battery rather quickly when using the Discrete GPU and four CPU cores running at the lowly 1500 MHz. 

Bugs

The Optimus NVIDIA video driver (v8.17.12.6871) from support.lenovo.com caused three BSOD’s and one unexpected system power failure in a short period of time. I have since turned off browser GPU hardware acceleration to see if that will stabilize the system.  The next course of action will be to install a newer video driver from NVIDIA (v8.17.12.7533).

Another bug encountered and documented in the Lenovo support forums is that once you go on battery, you must really shutdown and start back up to achieve full performance again.  If you simply plug the AC power cord back in, the CPU clock speed is throttled to 800 MHz and remains locked there.  That is easily reproduced by running at Turbo 3000 MHz, then pulling the power cord. It drops to 1500.  Plug the cord back in, and it drops to 800 and stays there.  Odd.

This is a rather annoying bug for people using the W520 for classroom work, meetings, or other scenarios that require battery use with suspend/wake cycles.

[Note] I wrote most of this on 7/17 and sent it to an internal discussion list for comment.  I have not seen any BSOD’s or any other stability issues since turning off hardware acceleration in IE9 and FireFox 5.

Comments

  • Anonymous
    August 04, 2011
    Hi Keith, In my experience the retail and beta NVIDIA drivers work better than the current Lenovo ones. No BSOD, no hardware accelleration issues. Also note that BIOS 1.27 is about to be made available. That version contains many more configurable items when it comes to behaviour on battery, as well as take away the 800Mhz issue. Cheers Willem