I bought the GA502DU a few weeks ago from Best Buy. I got a returned one that still looked brand new for a few hundred less than a new one would have cost. This laptop also suffered from the 400mhz locked CPU issue. I included a pic of my laptop running Prime95 and CPU temps and current clock speed. I didn't install Armory Crate. I really don't like the Microsoft store and I avoid it like the plague.
What I did do was to install the Ryzen Controller app from Github. When I first opened it I had task manager opened showing 0.39Ghz. Before I even opened any settings in the app it had already changed the speed of the proc to 2.4Ghz. After rebooting the machine several times it did not revert to 0.39Ghz. I played a few games and noticed really high fan speed so I opened CPUTemp and noticed mid 80's in temps. I had previously opened the case to install a Sabrent 2TB NVMe and a 16Gb 2666 So-Dimm and had noticed the fan holes being blocked. I removed the metal plates and the thin black plastic shims covering them and then removed the heatsinks, cleaned the dies on both GPU and CPU and applied new thermal paste.
At the time of this writing Prime95 has been running for about an 1:15 hours and the CPu temps are sitting at 67C at 3.4Ghz. If there is any other information anyone needs from me (IE what ver. Bios, Win 10 build etc.) Just ask.
