Topic: Spiking, Pops and Clicks... Need help!

I'm using Pro Tools 2018, running on a iMac Pro and I have the RME HDSPe MADI FX cards in a Sonnet enclosure. It doesn't happen every day, but every 3rd, 4th day, I see/hear spiking, popping and clicking in Pro Tools and the TotalMix window.

Here's what it looks like.

It's not a clock issue. What's I've done to narrow in on the problem is while the spiking is occurring, I turned off all my equipment except the Sonnet, and the iMac Pro and the spiking was still happening.

I tried another enclosure for the RME cards but that didn't fix the problem. I also tried different cables.

Does anyone know why this might be occurring? The same thing is happening when I try Studio One, Cubase and Logic Pro.