As others have noted, yes there is a cut-out with a grommet on the top of the shroud. This cut out is not only for PSU cables you want to pass through but it is the only realistic way for the bottom motherboard connections (USB headers, HD audio, front panel connections) to pass through. There is no space between the shroud and the motherboard to pass the connections to the back.
Since the case screams RGB everything, you have to plan your cabling very carefully. The back of the Mirror Black has extremely limited space for any routing and the gap to the glass is less than ideal. The case really needs to be 0.5 - 1 inch wider and taller.
I have the following installed and cabling was the biggest challenge I've ever had for a case.
H150i Pro (mounted front in push-pull) 3 LL120 push intake and the 3 120s that came with the cooler in back for pull.
2 LL140's at the top exhaust and 1 LL120 rear for exhaust.
All 6 RGB fans via second LED hub are connected to a Commander Pro LED 1. LED 2 has a 4 RGB strip. Included LED hub is for Front and PSU Shroud Corsair RGB logos. The included fans are dumped as the LL fans are so much better looking in the front glass.
I have 2 4TB HDDs for storage and no 2.5 SSDs (1 M.2 SSD on the motherboard for OS, etc.). The 2.5 SSD cages are removed and stuck in their place is the second LED hub and Commander Pro. There is no other place to put them.
Now I know why the PSU shroud orignally had no front cover. Space for PSU cables is an absolute joke with the cover there. If you use any type of custom PSU cables here, you have very significant space problems.
I use CableMod PSU cables for my AX1200i and they are long and not extremely flexible. Using only the 24pin ATX, CPU and 2 PCIe cables is alot to squeeze together in the back. There are also 2 sata cables for 6 sata connections (2 HDD, H150i, 2 LED hubs and the Commander Pro). One Molex cable for the internal USB hub since I need 4 USB 2.0 headers and the ASUS Maximus IX Code has only 1.
The USB hub is required for the following: Commander Pro, H150i, AX1200i and a Lighting Node Pro for 2 RGB strips that I have next the front case fans.
Needless to say, thats a lot to squeeze in the back. I still have to find a way to use the cable channel but there is too much to fit there.
The finished build is fantastic and the mirror glass is great but my god what a chore to cable route all that.