hit a brick wall overclocking my athlon 64 x2 5600+

[dopestuff]

hey peeps like the title states i have hit a brick wall overclocking my i think below specs:
Processor: AMD Athlon 64 X2
Model: 5600+
(Cpu) Stepping: F3
L2 Cache: 1024 KB
Clock: 2800 MHz
Socket: socket-AM2
Voltage: 1.30-1.35 V
Power: 89 W

i can't get much further then 3200 mhz (12 X 265) atm running 1.472 V (according to cpuZ )
even tried all the way up to 1.5 V but it just won't get stable (posting is no problem and also no crashes in games or atleast a lot of them)

i don't know if the problem is that my northbridge is not getting enough "juise" or that it is just the stable top (at a litle bit reasonable voltage)
i am not that far into overclocking that i can see that it is like the nb nog getting enough volts or just being the max overclock i can get...

i already set the cpu -> nb multiplier to 4X so to high HT speed is not the isseu and neither is the RAM cause thats rated at 1150 mhz (and "only" running at 1060 mhz)

ill post some specs under here...
mobo: m2n32 sli deluxe
proceccor: amd athlon 64 x2 5600+
RAM: OCZ DDR2 PC2-9200 Reaper HPC Edition
psu: corsair HX- 520
graphics card: sapphire radeon 4870 (running stock)

my cpu is wattercooled and at an ambient of 20 degrees it won't get to far over 40 degrees stressed

advice would be apreciated :)

[BeepBeep2]

I'm in the same situation...IHMO, highest 1.5v suicide was:
3.3ghz.
http://valid.canardpc.com/show_oc.php?id=488441

[Linux_Box]

Since it is water cooled, do you have decent air flow through the case? Sometimes WC cases don't have much air flow so NB, memory, mosfets, etc. get hot. If one of those is hot then it could cause OC problems (limits).