Q9650 overclocking on Asus P5QL Pro

Hey guys,
got some free time on my hands (finally) and decided to try clocking this rather old CPU I got. Not entirely new to clocking, but for the past few hours I've tried absolutely everything imaginable to get this thing stable over 3,8GHz.

Currently: running fine at 3743MHz (9x416), 1,325v in bios and 1,296v in cpu-z idle (speedstep is on). Funny thing is, when I load up prime95, the voltage in cpu-z drops to 1,256v
FSB termination: 1,4v
NB volt: 1,4v
SB volt: 1,5v
Spread spectrum off, load line calibration off, all clock twisters and boosters and such are off.
RAM: Adata OC edition 800+ DDR2 at 831MHz 4-4-4-12 at 2.1v
CPU temperature with prime95: 51 celsius (Cooler is a Xigmatek red scorpion)

Tried: running 9x420 at 1,35v, crashes after 20sec at desktop. Tried loosening RAM timings to 5-5-5-16, same results. PC makes quiet but audible buzz when I tried to run prime95 with these settings.

Any help is appreciated. As a side note, this was also the case with my previous PSU (Chieftec 1200w). Currently running a Corsair tx750 v2 (new).