The System X-Ray bar on the Amazon Fire TV and Fire TV Stick is a handy overlay with display, CPU, memory, and network information. It can be turned on and off using the hidden Developer Tools Menu on Fire OS 5 devices. It is meant to be used by developers to better understand what their apps are doing, but it can also be useful for common users to diagnose problems and locate misbehaving apps. Here is an overview of what each piece of information in the bar means.
The “HDMI Mode” lists the current resolution and refresh rate of the Fire TV. Above, “1080p” is the resolution and “60” is the refresh rate. The resolution is usually 480p, 720p, 1080p, or 2160p, while the refresh rate can be 24, 25, 30, 50, or 60. The “HDCP 1.0” indicates the version of HDCP content protection encryption used by the Fire TV on the HDMI connection.
This shows how much of the processing power of the device is being used. The Fire TV 1 and 2 have four CPU cores, which is why there are four columns. The Fire TV Stick has two CPU cores, so only the first two columns will show activity on the Fire TV Stick. The level indicator on each column will change color to indicate how much processing power is currently being used by each core. Light green is the lowest color, then dark green, then yellow, then orange, and then red.
If your device is feeling sluggish or not responsive, checking to see if something is using a lot of processing power should be one of the first things you do. If you do have high CPU usage, you can start force quitting apps one by one to see which one causes the CPU usage to drop.
The memory section refers to how much RAM is being used. This should not be confused with how much internal storage is being used. The Fire TV 1 and 2 have 2 GB of RAM, while the Fire TV Stick has 1 GB of RAM. The blue portion of the graph, and corresponding value below, indicates how much memory the active foreground app is using. The package name of the active foreground app is also displayed below the memory graph. Above, “com.amazon.tv.launcher” is the foreground app’s package name, which is the Fire TV home screen app. The gray bar, and corresponding value below, indicates how much memory is being used by the entire system as a whole. The white bar, and corresponding value below, indicates how much free memory is available. In the image above, 121.2 MB of memory is being used by the home screen launcher app, 1.1 GB of memory is being used by the system as a whole, leaving 978.5 MB of memory free.
If there is no free memory, it is usually an indication of an app with a memory leak. Again, you can force quit apps one at a time to see which one is the culprit.
The “RSSI” bar, short for Received Signal Strength Indication, indicates the WiFi signal strength of the device. The higher the bar is, the better the device’s WiFi signal is. Below the bar is the numerical value of the WiFi signal strength, measured in dBm. Note that this value is always negative. The closer the value is to zero, the better the signal strength is. For example, a value of -5 dBm is a better signal strength than a value of -34 dBm. If the Fire TV is connected via a wired ethernet cable, the RSSI bar will not be displayed.
The “Total Download Speed” value, which is 18.2 Mbps above, is the rate at which the Fire TV is currently downloading data. This is not a maximum speed indicator. It is just what the device is doing at that given moment.
The “FG App” value, which is 0 bps above, tells you the network speed at which the foreground app is downloading. In the case of the image above, the foreground app is the Fire TV home screen launcher, so it is not downloading anything and another app is doing the downloading in the background.