Should I use 2x8GB at 3600MHz or 4x8GB at 3400MHz?

I'm currently testing my RAM setup and I have 16GB of DDR4 (2x8GB) running at 3600MHz. My motherboard is an MSI B550 Gaming Plus and my CPU is the Ryzen 7 3700X. The 3600MHz speed works fine with the two sticks, but when I try to add four sticks and set the speed to 3600MHz, I get a black screen. I'm thinking 3400MHz might be more stable with four sticks. Given that I can't return the additional RAM, I'm trying to figure out if it's better to run 2x8GB at 3600MHz or 4x8GB at 3400MHz. If 3400MHz doesn't work out, what other options do I have? Thanks for any help!