Yeah,Sedna, not sure whether it works on 5.03GEN-C
Basically to hack your motherboard you need to download 5.03GEN-C, unzip to ms0:\PSP\Game folder on your memory stick and while in ChickHEN/MHUSpeed go along to game and click it to enable.
Judging by the fact you have a 16gb memory stick I'm gonna go out on a limb and say you're going to put a LOT of stuff on your PSP. I suggest you install the "Game Categories Plugin" which basically allow you to seperate your games instead of having one huge-ass list. Also download the "Homebrew Sorter GUI" to order them however you want (the PSP's ordering system is absolute balls)
Also since you're using a PHA motherboard I suggest you change from ChickHENR2 to MHUSpeedv3 which is a lot less random in getting to start (though there is an element of it)