Actually the sticks are in the first two slots of the motherboard.
Apparently the problem is now fixed. I went to check the settings in the bios to try enabling the X.M.P. (Extreme memory profile) but the clock speed had apparently gone up to the proper speed.
I had rebooted twice after updating the bios and the clock speed still hadn't changed after those restarts. I haven't changed anything else but now it's working properly, it seems.
Thanks anyway!