Monitor going into power save mode when plugged in with HDMI cable

It's a desktop, and nope, all of the hardware is the same as it was when I bought it, and it only has one HDMI port. I got this computer in February so I don't think I'd need to look for driver updates for the motherboard :\

Just because you bought it recently that doesn't mean it doesn't have updates. Some hardware have serious issues that get patched within weeks of release.

That said, outside of driver updates and the possibility of your HDMI port being dead (on either end) I don't really think there's much I can do to help you