Comment by walrus01
3 years ago
Something I recently observed is that cutting edge, current generation gaming-marketed x86-64 motherboards for single socket CPUs, both Intel and AMD, still come with a single PS/2 mouse port on the rear I/O plate.
I read something about this being intended for use with high end wired gaming mice, where the end to end latency between mouse and cursor movement is theoretically lower if the signal doesn't go through the USB bus on the motherboard, but rather through whatever legacy PS/2 interface is talking to the equivalent-of-northbridge chipset.
Some still have two, for a keyboard and mouse:
https://static.tweaktown.com/content/1/0/10071_10_asus-rog-m...
Latency is lower because it's interrupt-based and much simpler than the polled USB stack. IMHO if you're going to always have a keyboard and mouse connected to the computer, it makes perfect sense to keep them on the dedicated simpler interface instead of the general USB; especially when the dedicated interface will be more reliable. The industry may be partly moving away from the "legacy-free USB everything" trend that started in the 2000s, finally.
AFAIK all SuperIOs support a pair of PS/2 ports, so from a BoM perspective it's not an extra cost to the manufacturer, but they still market it as a premium feature.