Modchipped PS1, discs now spin half-speed?

So I just got done chipping my PS1 (PU-23 board) using PsNee on an Arduino Pro Mini board. It works perfectly fine, aside from one thing: the disc spins hella slow now. No idea why. The game still boots, but FMV and stuff is slow and choppy. Everything seems to work just fine aside from that though.

Note: I only have one game to test with at the moment since I have no blank CDs to test backups with. Also I have no controller.
The Pro Mini I used is a 5V, 16MHz model with the appropriate...

Modchipped PS1, discs now spin half-speed?