Hardware Monitor

Known Issues

There are currently no known problems that require additional documentation.

End-of-Life Notice: Hardware Monitor is no longer in development (Why?)

Release Notes

The screen display might not work correctly with macOS Sierra: If you are using the output channel “Screen Display” with one of the latest versions of the Macintosh operating system, sensor data may not be shown correctly. Instead, pixel noise appears in the display area. The exact circumstances will depend on the graphics chip that is currently in use, the exact version of macOS, and your personal preferences for the screen display feature.

Workaround: This is a known defect with specific graphics drivers that are shipped with macOS Sierra. It is currently unknown when and if Apple will fix this problem. As a workaround, reduce the width of the screen display, either by switching it to vertical mode, or by removing sensor entries from the list.

The menu of the menu-bar status display may not be complete in macOS Sierra, and the Lite version of the application cannot be quit with this menu. When the menu attached to the status item at the right side of the menu bar is opened, the latest versions of the Macintosh operating system may not show all entries. The lowermost items are missing. In case of the “Lite” version, this additionally means that the items to quit the application or to control remote operation cannot be selected.

Workaround: This is a known defect of macOS Sierra. It is currently unknown when and if Apple will fix this problem. As a workaround, reconfigure the output channel “menu bar” to show less sensors.

After updating from a previous version of the software, an ambient air sensor has the status “disconnected” on some iMacs: If you have updated to Hardware Monitor 5.1 or later from an older version of the application and you have used the program on an iMac published later than the “Late 2013” model series, the temperature sensor labeled Ambient Air will no longer be displayed. In your list of preference settings for this sensor, it is shown as being disconnected.

This is the correct and intended behavior. Although the aforementioned iMac model series contain a sensor with that name and function, this sensor is known not to work as expected, so its readings should be suppressed. Hardware Monitor 5.1 and later will do so, but older versions of the application may have created display preferences for this sensor which have been stored in your settings. You can safely remove this entry from your sensor preferences.

Monitoring GPU sensors on computers which have two independent switchable graphics units is not officially supported by the application: Some specific Apple computers come with two alternative GPU solutions: One energy-saving graphics processor inside the main processor and one high-performance graphics processor on an external chip. Such computer models show the option Automatic graphics switching (or similar) in the pane Energy Saver of System Preferences. If the option is active, which is the recommended default setting, the computer may change GPUs during operation, switching one graphics processor off and the other graphics processor on. All sensors of the GPU currently powered down will also become inactive. Due to architectural problems, there can be unexpected side effects in the application when you monitor such sensors.

Workaround: We don’t recommend to monitor any of the GPU sensors for such computer models. Identify all graphics processor sensors in the pane Sensors of the Preferences panel of the application and set the check mark Data query: Don’t acquire readings from this sensor for each of them.

When running monitoring utilities of other vendors which also access S.M.A.R.T. features of hard drives, Hardware Monitor can be blocked from accessing S.M.A.R.T. readings: Certain low-quality monitoring applications of third-party vendors are known to reserve exclusive access to the S.M.A.R.T. interfaces of hard drives. When running such applications, neither Hardware Monitor, nor other applications, like Apple’s Disk Utility or System Information, can access any S.M.A.R.T. features until the misbehaving application is quit. S.M.A.R.T. sensors or probes show a value of “—”, the Drive Overview window shows “S.M.A.R.T. status: not available”.

Workaround: Either disable S.M.A.R.T. monitoring in the third-party application, or contact its vendor to have the problem resolved. It is bad practice to use exclusive access to the S.M.A.R.T. interfaces of hard drives.

Frequently Asked Questions

What is a S.M.A.R.T. hard disk sensor?

S.M.A.R.T. is the abbreviation of Self Monitoring, Analysis, and Reporting Technology. It is an industry standard introduced in 1992 to react earlier on hard disk failures. A hard disk supporting the S.M.A.R.T. standard monitors itself with its own micro processor and allows the operating system to request readouts that indicate whether operational parameters have changed in such a way that the hard disk might become defective in the near future. In that case, the hard disk can be replaced before any data is lost.

Some hard disk manufacturers allow the computer to request additional detail information, e.g. the current operating temperature of the disk. However, this feature is not an official part of the S.M.A.R.T. standards. Not every disk supporting S.M.A.R.T. is capable of providing temperature readings. Either the data is not measured at all, or the hard disk manufacturer did not publish how the data can be read out from the disk controller.

Hardware Monitor analyzes all hard disks connected to your computer if they include accessible temperature sensors. Each disk is tested for compliance with the S.M.A.R.T. standard. If the disk is supporting S.M.A.R.T. and the procedure for reading the temperature value of this particular model is known, the readings are automatically acquired by the software.

Why is no temperature displayed for my external FireWire or USB hard disk?

Nearly all FireWire or USB hard disks are in fact SATA hard disks accessed via a “FireWire/USB to SATA bridge device”. Those bridge chips only translate a subset of the ATA commands between the FireWire/USB and the ATA protocol standards. In particular, commands to transfer S.M.A.R.T. diagnostic data (which are needed to access the temperature sensors inside the drives) are usually not supported. For this reason it is technically impossible to transport temperature data across a bridge. There are technical workarounds for this problem, but Apple currently does not support them in OS X.

Use the menu item Window > Show Drive Overview or press ⌘+8 to display the transport protocols of all disk drives and their S.M.A.R.T. capabilities.

Why is no temperature displayed for my solid state drive (SSD)?

Not all drives compliant with the S.M.A.R.T. standard are providing temperature values. Different from conventional hard disks, the ambient temperature is not an important factor to estimate the remaining lifetime of an SSD. For this reason, many SSDs don’t have any temperature sensors.

Why is my hard disk not put into sleep mode if the application is running?

If one or more hard disks are equipped with temperature sensors, the values will be read out in regular intervals. OS X is interpreting this as access to the hard disk which causes the disk not to be put into sleep mode.

You can change this behavior by enabling the disk saver feature of the application: When you are inactive and the computer is not really in use for some period of time, the program can automatically stop all sensor communication with your hard drive(s). This allows the standard sleep feature of the hard drives to become active. Just open the preferences window, go to the General pane and set the pop-up menu of the option Disk Saver to the desired time-interval for user inactivity.

The sensor X shows the reading Y. Is this normal?

If you want to find out whether a sensor value is within normal limits, select the menu item Window > Show Overview (or press ⌘+1) and look for the limits in the third and fourth columns of the sensor table. They contain the known official limits Apple has specified for readings acquired at the given sensor locations. If no limit is given in the table, this either means that it does not make sense to specify a limit for this particular sensor (e.g. the battery capacity should not have limits), or Apple hasn’t published any specifications for this sensor.

Note that all up-to-date Macintosh models automatically shut down or enter sleep mode if one of the readings exceeds a critical limit. For this reason it is impossible that your computer can be damaged in an over-temperature condition.

Why are the temperature values for some of my FB-DIM modules in the Mac Pro or Xserve missing while others are displayed fine?

This indicates that you are using FB-DIMMs which are not fully compatible with Macintosh systems. In most cases, this is caused by errors in the firmware of the AMB chip (Advanced Memory Buffer) controlling the module. You should replace these incompatible modules: If your system is not receiving valid temperature readings from the FB-DIMMs, the cooling control for the RAM temperature zone won’t work correctly.

Are readings of more than 90°C (194°F) for FB-DIM modules not a bit high?

No, temperatures in that range are normal for FB-DIMMs and are no cause for concern. Each FB-DIMM contains its own controller, called Advanced Memory Buffer (AMB). An AMB also contains an internal sensor which measures temperature directly inside the chip. The specified maximum temperature range of an FB-DIMM, measured by the AMB, usually lies in the interval between 95°C and 125°C (203°F .. 257°F). It will vary from manufacturer to manufacturer, a typical value is 110°C (230°F). If you like to know the exact specifications for your FB-DIM modules, note the part number and manufacturer of the respective modules (printed on the label of each module), and download the data sheets for those parts from the manufacturer. Nearly all chip manufacturers and RAM vendors publish the specifications at their web sites.

How many registration keys do I have to purchase when monitoring several computers with the remote access feature of Hardware Monitor?

There is one simple rule: You need one registration key for each computer that is monitored at the same time.

Registration keys for Hardware Monitor and Hardware Monitor Remote are interchangeable. So if you are running Hardware Monitor and Hardware Monitor Remote on one computer you’ll need only one key for this system. If another copy of Hardware Monitor connects to this system, it will need a second key because then we’ll have a network of two monitored computers which are in use at the same time.

Another example: You have 2 computers that should be capable of monitoring each other. In this case you install the applications 4 times (a copy of Hardware Monitor and a copy of Hardware Monitor Remote on both systems), but you only need to buy 2 registration keys.

How can Hardware Monitor warn me when a RAID set or S.M.A.R.T. drive is failing?

This can be done in two simple steps:

  1. Open the pane Probes in the Preferences window of Hardware Monitor and create a RAID or S.M.A.R.T. probe for the drive in question.
  2. Go to the pane Alerts, use the + button next to the table of sensors to be monitored and drag the newly created probe entry from the drawer into the table. Make sure the entry is still selected, remove the checkmark at Trigger alarm: When value exceeds threshold of, and set a checkmark at Trigger alarm: When value falls below, entering a value of 1.

You can then select which of the possible alert actions should be taken. If you want to continuously monitor drives, it is recommended to add Hardware Monitor to your list of login items.

How can I remove the driver “BRESINKx86Monitoring” installed by old versions?

A device driver with this name could optionally be installed for “extended x86 sensor support” when you have been using old versions of Hardware Monitor on Intel-based Macs running an operating system between Mac OS X 10.4.6 and OS X 10.9.5.

When you upgraded such a system to OS X 10.10 or later, the driver was automatically deactivated. Although it has no negative effect on your system, you might like to remove the outdated driver files. This has always been possible with the menu item Monitor > Remove driver for extended x86 sensor support.

As of version 5.0, this menu item is no longer present. However, you can still remove the driver as follows:

  1. Ensure you are logged in as user with administrative rights.
  2. Use the Finder to open the folder Library at the topmost level of your system volume, and inside it, the folder StartupItems. If the driver is still installed, you will see the folder BRESINKx86Monitoring at this location.
  3. Drag the folder BRESINKx86Monitoring to the Trash. OS X may ask for your administrator password.