E2314H's going bad (Purple Screen)

Hello all!

I have around 25 Dell monitors (E2314H) that were purchased back around 5 years ago. These monitors are used in a small call center and are on 24/7. They're been running good up until lately. I've had 5 monitors to go bad within the last 2 months. They will get a purple hue and the purple hue will start rolling down the screen and the screens starts glitching and then the whole thing will start going from purple to normal and back again. I've attached a photo of what it looks like. Now am I to assume that they've all started going bad all at once? They are all connected to Dell Dell OptiPlex 3010's. I've swapped the monitors out with different monitors I had laying around and no problem, and I can move the defective monitor to servers and other computer in the building with the same result which would seem to point everything at the monitor going bad. It's just going to be hard to tell the employer that all the monitors are just going bad without a cause. 

Thanks in advance for any help!