Last Updated on February 23, 2024 by Dave Farquhar
A lot of modern computers don’t come with PS/2 ports anymore, the reason being that USB replaced most of the ways we used to connect external peripherals to computers. But sometimes you need those ports on a modern or modern-ish computer. Here’s how to add PS/2 ports to a Dell Optiplex computer.
Why add PS/2 ports to a computer?
USB is convenient, but sometimes you have legacy devices that plug into the old connectors. And that’s one reason why so many PC makers were reluctant to remove legacy connectors like PS/2 keyboard and mouse and RS-232. It costs money to put them there, and margins on PCs are extremely thin, but the market is also super competitive. You don’t want to leave yourself open to losing a million-dollar deal over $2 worth of connectors. That’s why Dell made it possible to add them into Optiplex models.
On a hobbyist level, now that Microsoft has tightened up the hardware requirements for Windows 11, that means every Dell Optiplex made before late 2017 has a use by date. The day after Windows 10 goes out of support, which is October 15, 2025 if you’re counting, those machines are obsolete.
That means if you want a cheap, high quality desktop to turn into a Windows XP or Windows 7 retro rig, you can pick up a Dell Optiplex for very little money. But if you are looking to turn it into a retro rig, you might want PS/2 and RS-232 ports. It will allow you to connect a wider variety of input devices, and the RS-232 port can be very useful for sending data over to other retro computers. Even if you aren’t terribly nostalgic for this particular era of computers, it is extremely useful to have a slightly older computer that can accept a lot of different input devices to use as a bridge between the modern and retro world.
If you can live with giving up an expansion slot, you can add PS/2 and RS-232 ports to many Dell Optiplex machines that lack them. There is a 24 pin header on the motherboard with all of the necessary signals on it. All you need is a breakout board that fits neatly in place of a PCI bracket.
Add legacy ports to a Dell Optiplex
The part number for the two boards changed over the years, but the surplus market is full of them. The silkscreen on the board reads “Tigris PS/2 serial port card.” You’ll also find the numbers 13564-1 and 48 3JS24 011 on the board.
First, you want to make sure that your motherboard has the header. The placement of the header varies. On two systems I was able to check, on the mini tower system, the header was close to the processor. On the small form factor unit, the pin header was close to the video connectors. The header is labeled KB, MS, SERIAL.
The board itself costs around $20. I recommend looking earlier in the week. Here’s why.
The board for the small form factor units has one PS/2 port and one RS-232 port. The board for mini tower units has a pair of PS/2 ports and one RS-232 board. The silk screen on the boards is the same, so you will have to pay attention to the picture to make sure you get the right one.
The higher profile board works in the following Optiplex models:
- GX620
- 360/760
- 390
- 3010
- 3020
- 740/745/755
- 380/580/780
The low profile board works on the following small form factor models:
- 3020 SFF
- 390 DT
- 7020 DT
- 790 DT
- 990 DT
Installation is simple. The cable on the board plugs into the pin header labeled KB, MS, SERIAL on the motherboard. It is keyed, so you can’t plug it in the wrong way. Remove the backplate from an unused PCI slot, place the board in its place, and clamp it back down. Close the case cover, plug in your legacy devices, and Windows should detect them and let you put them to use.
David Farquhar is a computer security professional, entrepreneur, and author. He started his career as a part-time computer technician in 1994, worked his way up to system administrator by 1997, and has specialized in vulnerability management since 2013. He invests in real estate on the side and his hobbies include O gauge trains, baseball cards, and retro computers and video games. A University of Missouri graduate, he holds CISSP and Security+ certifications. He lives in St. Louis with his family.
Additional data points: I just opened my OptiPlex 760 desktop model (which has 3 half-height expansion slots). The connector is between the CPU and the floppy drive connector, is black, and is labeled SERIAL2. There’s a Dell sticker with a QR code and 0R230R on the motherboard; Google search says this is the motherboard model number.
Same story in my OptiPlex 380 minitower; it’s also labeled SERIAL2. Motherboard model number 0HN7XN.