Why Do Motherboards Still Have PS/2 Ports?

Motherboards still have PS/2 ports because they offer guaranteed BIOS access, zero input lag through hardware interrupts, and reliable operation when USB controllers fail. While USB has replaced PS/2 for most users, system builders, IT professionals, competitive gamers, and secure facilities continue to rely on these 6-pin mini-DIN connectors for specific technical advantages that USB cannot fully match.

What Is a PS/2 Port and How Does It Work?

The PS/2 port is a 6-pin mini-DIN connector that IBM introduced with its Personal System/2 computer line. These ports connect keyboards and mice directly to the motherboard's chipset using dedicated interrupt request lines. The purple port handles keyboards while the green port handles mice.

Unlike USB devices that share bandwidth and require software drivers, PS/2 peripherals communicate through hardware interrupts. When you press a key on a PS/2 keyboard, the signal travels directly to the CPU through IRQ1 (interrupt request line 1) without waiting for the operating system to check for input.

Does PS/2 Actually Have Less Input Lag Than USB?

PS/2 connections do have slightly less latency than USB in theory, but the real world difference is extremely small. PS/2 keyboards respond through hardware interrupts in about 1 millisecond or less. USB keyboards operating at a 1000Hz polling rate add an average of 0.5 milliseconds of delay.

For most people, this 0.5-1 millisecond difference is impossible to notice. However, some competitive esports players and rhythm game enthusiasts prefer PS/2 because every bit of latency matters at the highest skill levels. Modern gaming keyboards with high polling rates have largely closed this gap, making the practical difference negligible for typical use.

Why Do IT Professionals Keep PS/2 Keyboards?

System administrators and computer technicians value PS/2 keyboards because they work at every stage of the boot process. When you need to enter BIOS settings, update firmware, or troubleshoot a system that won't start properly, a PS/2 keyboard provides guaranteed input.

According to motherboard manufacturers like ASUS and MSI, including PS/2 ports remains standard on enthusiast and workstation boards specifically for this BIOS accessibility. The ASUS Republic of Gamers lineup and professional workstation boards continue including these ports despite the extra circuit board space they require.

What About N-Key Rollover?

PS/2 keyboards support true N-Key Rollover (NKRO), meaning they can register every key pressed at the same time without any limit. The original USB specification only allowed 6 simultaneous key presses plus modifier keys like Shift and Control. This limitation existed because USB keyboards send data in packets with a fixed size.

Modern USB keyboards work around this limitation through custom drivers or by using multiple virtual keyboard endpoints. Most quality gaming keyboards now achieve full NKRO over USB. However, PS/2 had unlimited simultaneous key detection built in from the start, which is why mechanical keyboard enthusiasts sometimes prefer this older connection.

Why Do Secure Facilities Disable USB but Keep PS/2?

Government agencies, financial institutions, and other high security environments often disable USB ports entirely to prevent data theft. USB drives can easily copy sensitive files, and USB devices can introduce malware through a technique called BadUSB attacks.

PS/2 ports cannot transfer files or run executable code. They only send keyboard scan codes and mouse movement data. This makes them inherently safer for sensitive environments where preventing unauthorized data transfer is critical. Workers in these facilities can still use keyboards and mice normally while USB access remains completely blocked.

Are Motherboards Removing PS/2 Ports?

Many modern motherboards, especially compact Mini-ITX and budget models, have dropped PS/2 ports entirely. Space on the rear I/O panel is limited, and manufacturers often prioritize extra USB ports, additional display outputs, or faster networking connections instead.

However, enthusiast boards, workstation motherboards, and server platforms continue including at least one combo PS/2 port (a single port that works with either keyboards or mice). This trend reflects the ongoing demand from professional users who need guaranteed peripheral access during system setup and troubleshooting.

Motherboard Categories and PS/2 Availability

Should You Buy a Motherboard With PS/2 Ports?

For most home users, PS/2 ports are not essential. Modern BIOS systems handle USB keyboards reliably during boot, and the latency difference is too small to notice in everyday use. If your current keyboard and mouse are USB, you have no practical reason to switch.

Consider prioritizing PS/2 availability if you build or repair computers frequently, own vintage mechanical keyboards with PS/2 connections, work in security conscious environments, or need absolute certainty that your keyboard will function during any boot scenario.