It’s hard to deny that Microsoft’s Windows 7 was one of the most beloved operating systems with many beloved features and some would certainly argue that its influence was just as great as those of Windows 95 and Windows XP before it. Although support for Windows 7 ended more than two years ago, the 2009 operating system is still the third most popular with about 10% market share.

One of the reasons for its popularity was its significant system requirements, as it could run well on its minimum requirements. All you need is a single-core 1GHz processor and 1GB (32-bit) / 2GB (64-bit) system memory. And despite such low requirements, the software was designed to support Up to 256 cores/threads in 64-bit mode which emphasizes that it is quite forward-looking. Although Microsoft stuck to the same requirements until Windows 10, it’s generally never quite as smooth an experience on the new, much heavier operating system.

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

Apart from this, some big changes have also been made. The entire OOBE folder (c:\windows\system32\oobe folder) was deleted and registry changes were made to mimic “pseudo-OOBE mode”. The BCD (Boot Configuration Data) has also been adjusted so that it boots into safe mode even when the “Run Windows normally” option is selected. To release additional bloat, the GUI components have also been disabled.

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

In the end it was a fun experiment and most people who still run Windows 7 as their daily driver probably do so on much faster computers anyway. And if that PC qualifies for Windows 11, Microsoft says you can certainly upgrade to its latest operating system, though it will require a clean install.

Source: NTDEV (Twitter) (1), (2) Through Tom’s hardware