Windows 7 was designed to run on a mere 5 MHz Pentium, 128 MB RAM, and it worked, mostly.

It’s hard to deny that Microsoft’s Windows 7 was one of the most beloved operating systems with so many features, and some could certainly argue that its influence was as big as its predecessor. Windows 95 and Windows XP. While support for Windows 7 ended two years ago, the 2009 OS is still in third place with about 10% market share.

One of the reasons for its popularity was its reasonable system requirements as it could actually run well on its minimum requirements. All you needed was a 1GHz single-core CPU and 1GB (32-bit) / 2GB (64-bit) system memory. And even with such low requirements, the software was designed to support it. Up to 256 cores/threads Highlighting that in 64-bit mode is quite forward-looking. Although Microsoft stuck with the same requirements until Windows 10, it’s generally not such a smooth experience on newer, heavier OSes.

To test how low one could go with Windows 7, Twitter user and Windows enthusiast NTDEV tried running it on a 5MHz Pentium-S processor – 200 times lower than the official requirement – and 128MB of RAM. You can see in the image below that the Pentium chip is running at 50MHz. NTDEV notes here that LogonUI refuses to load anything below that. The 5MHz clock was obtained by modifying the source code of the 86Box, the virtual machine where the test was performed.

Apart from this, several important amendments were also made. The entire OOBE folder (c:\windows\system32\oobe folder) was deleted and registry tweaks were made to simulate a “pseudo-OOBE state”. BCD (Boot Configuration Data) was also tweaked so that it would boot into Safe Mode even when the “Start Windows Normal” option was selected. For further de-bloating, GUI elements were also disabled.

NTDEV managed to boot into Windows 7 Ultimate build 7601 SP1 after about 28 minutes. The system was stable with WCPUCLK or Real Time Clock Checker verifying that the system is indeed running at 5Mhz.

Ultimately it was a fun experience and most people who are still running Windows 7 as their daily driver are probably doing so on much faster PCs anyway. And if the PC meets the requirements for Windows 11, Microsoft says you can certainly upgrade to its latest OS, though it will require a clean install.

Source: NTDEV (Twitter) (1), (2) through Tom’s Hardware