Next steps on Phenom II X4 965BE OC from 4Ghz to 4.2Ghz?

[JCB75]

I've hit a wall on a OC. Looking for what to do next to try to get up to 4.2Ghz. I'm currently at 4Ghz flat with the following values.

Asus M4A785TD-V Evo
Phenom II X4 965BE C3 3.4 Ghz stock
Coolermaster Nepton 240m Water Cooler
Sapphire Radeon HD5770 OC'd 860/1200 by AMD Overdrive from gfx driver package
G.Skill 2x4GB, 2x2GB 9-9-9-24 (These are the same chip in different sized sets. Larger set in channel A)
FSB: 200
CPU Voltage: 1.56250
CPU/NB Voltage: 1.375
NB Frequency: 2400
NB Voltage: 1.415
Multiplier: x20
DRAM Speed: 800 OC'd from 667
DRAM Voltage: 1.8
PSU: Corsair 700W
Bios ACC: Disabled
Bios LLC: 0%
Bios C1E: Disabled

So far I'm an hour into OCCT. Temps are at 55C max, Vcore 1.65 max. When I up the multiplier to x21.5 I get graphic corruption, and freeze within a minute under load. No BSOD's. What is the likely culprit? Sort of new to this but have been soaking up info like a sponge. Looking for the proper order of things to try from here. The cooler seems like it has a lot of headroom left. I've seen someone report 4.2Ghz on this combo but mine isn't holding up. I can get to 4GHz, but not 4.1Ghz. Target is 4.2Ghz. I have yet to ring out any hard limits. I started with these values from someone with the same kit. Because I'm new detail is appreciated. Currently reading up on RAM timings as a hunch. Thank you!

 

[JCB75]

Does the graphics freeze indicate that I might need a little more voltage on the PCIe for the graphics card?

 

[DCNOS18]

Hi, how many watts is your PSU? Sometimes if you overclock too hard the PSU won't be able to send the power your components need.

 

[JCB75]

Hi, how many watts is your PSU? Sometimes if you overclock too hard the PSU won't be able to send the power your components need.

Updated. It's a 700W Corsair. System currently has 4 mechanical hard drives connected. About to add an LSI RAID card, two more mechanical WD Blacks, and an SSD once the RAID card arrives. Seem okay?

 

[JCB75]

I have the machine plugged into an EZ Watt meter. At full 4.0Ghz load the meter is ranging from 400W min to 500W max. That's with everything I plug into the machine 24/7; such as external drives.

 

[DCNOS18]

Eh. I don't know. It kinda seems like your pushing it. Especially since everything is at 100% load. Maybe try playing with the cpu voltage just a bit.

 

[JCB75]

Eh. I don't know. It kinda seems like your pushing it. Especially since everything is at 100% load. Maybe try playing with the cpu voltage just a bit.

Those are the values under stress with OCCT. I'll take a look at the power draw on the meter at 4.1Ghz.