How to see what your PC was doing yesterday

You can see what your PC was doing yesterday by opening the History page in Pulse by Zaweba and choosing Yesterday in the Show selector. It shows a CPU and memory graph and a network graph for the day, with totals, plus lists of the apps that used the most CPU time and the most network data. It works because Pulse records a summary of the PC every minute and keeps it for 30 days by default.

Windows' own Task Manager only shows the present. Once the moment has passed, the evidence has gone. A monitor with a memory lets you answer questions after the event, which is when most people think to ask them.

What needs to be in place

Pulse has to have been running yesterday for there to be anything to show. It is designed to be left on: closing the window keeps it in the tray, and the "Start Pulse when I sign in" option in Settings starts it there each time you log in. In the background it is light, about 0.1 per cent CPU and 70 MB on the test PC.

Each minute Pulse stores the machine's CPU, memory, GPU, network and disk use, each busy app's CPU seconds, network and disk bytes and peak memory, and each sensor's peak and average. All of it goes into a local file in your AppData folder. Settings > History sets how many days to keep, from 1 to 365, and shows how many minutes are recorded so far.

Reading yesterday's record

Open the History page with Ctrl+3, from the View menu or from the tray menu. Choose Yesterday. The graphs fill in for the whole day, so you can see at a glance when the PC was busy and when it was idle. Look for the shapes that stand out: a long plateau of high CPU, a burst of network traffic in the middle of the night, memory climbing steadily through the afternoon.

Below the graphs, Top CPU users ranks apps by the processor time they used over the day. This is often more telling than a live view, because a program that ran flat out for an hour while you were out of the room will rank highly even though it is quiet now. Top bandwidth users does the same for network data, which is the list to check when a data allowance has gone down unexpectedly.

There is also a list of temperature peaks for the period, each with the three busiest apps in that minute, so a hot or noisy moment can be linked to the program behind it.

Turning a pattern into an answer

The graphs tell you when, and the lists tell you who. Put them together and most mysteries clear up. A spike at the same time as a backup program tops the CPU list is probably the backup. Heavy overnight traffic with a game launcher at the top of the bandwidth list is probably an update.

If you want to compare against a normal day, switch the selector to Today or This week. This week is useful for spotting habits, such as a sync that runs every evening or a scan that runs each morning.

When something keeps happening

If the same thing turns up day after day, the Alerts page can watch for it for you. You can be warned about high memory for a number of minutes, an app using too much data in a day, a hot sensor or a drive whose health declines. Each alert arrives once as a Windows notification and goes into the alert log. Then, the next time you wonder what the PC was up to, Pulse by Zaweba may already have told you.