Monitor not waking up from sleep

Hi,

I built a hackintosh with the buying guide from tonymacx86, and so far it worked really well. However, I've recently upgraded to a 4K dell monitor and now, when I wake the computer from sleep, I can sometimes see the login screen for a brief moment, but then the monitor goes blank and stops receiving input from the GPU. I have a discrete EVGA GTX 1080.

My working theory is that the monitor wakes up much faster than the old one, so the GPU misses it and doesn't initialize properly on wake.

How can I attempt to fix this? Thanks in advance :)