Hello, I currently got in head to OC my I7-930 to 4.51 ghz, but changing the CPU voltage is just not enough, so i'm seeking advice from you guys.
My build is:
ASUS P6T58X Premium
G. Skill ram 1.5v 7-8-7-24-2N (Stock)
2x ATI 5970
CPU Ratio Setting - [21.0]
C1E Support - [Enabled]
Hardware Prefetcher - [Enabled]
Adjacent Cache Line Prefetcher - [Enabled]
Intel Virtualization Tech - [Enabled]
CPU TM Function - [Enabled]
Execute Disabled Bit - [Enabled]
Intel HT Technology - [Enabled]
Active Processor Cores - [All]
A20M - [disabled]
Intel Speedstep Tech - [Enabled]
Intel C-STATE Tech - [Disabled]
BCLK Frequency - 
PCIE Fequency - 
DRAM Frequency - [Auto]
UCLK Frequency - [Auto]
QPI Link Data Rate - [7550's mt/s] (Want that OC'ed somehow, think i need to tweak the QPI/DRAM Core Voltage, there is a dangerous limit there, which i don't know what is)
Dram Timing Control:
1st Information - 7-8-7-24
2nd Information - 2N
Load-Line Calibration - [Disabled]
CPU Differential Amplitude - [Auto]
CPU Voltage - [1.45000]
CPU PLL Voltage - [1.88]
QPI-Dram Voltage - [Auto]
IOH Voltage - [Auto]
IOH PCIE Voltage - [Auto]
ICH Voltage- [Auto]
ICH PCIE voltage - [Auto]
DRAM Bus Voltage - [1.64]
DRAM REF Voltage - [Auto]
CPU Spread Spectrum - [Disabled]
PCIE Spectrum - [Auto]
CPU Clock Skew -[Auto]
IOH Clock Skew - [Auto]
Given up trying to find something that will explain, its just confusing and I never get that straight answers I'm looking for.
-What would/could make my CPU more stable?
Disable C1E and Speedstep. They can be turned back on once you have a stable OC.
Enable load-line calibration.
QPI is like the fsb. 1.4v is the safe max, try to stay around 1.3-1.35v
Simply put PLL voltage helps keep the cpu frequencies from oscillating under load so if the frequency is jumping even a few mhz then upping the PLL voltage can help stabilize it but to much can actualy make it unstable.
Try 1.35v QPI
and try to set PLL only a few notches up from the original setting before you turned it up, or just set it to auto.
"think i need to tweak the QPI/DRAM Core Voltage, there is a dangerous limit there, which i don't know what is"
The voltage difference between the QPI and ram voltage should be less than .5v.
4.5ghz isnt a simple clock bump and voltage adjustment.
If you have given up trying to find something to explain then you need to also give up on overclocking to that speed.
If you dont understand what you are setting/adjusting your chances of damaging your system are extremely high at those frequencies.
3 suggestions that you would be wise to think about,
1. Anyone willing to offer settings and advice to punch out those speeds I wouldnt trust to replace my cmos battery let alone o/c my rig. You will find that the people that have O/C'd to high speeds wont be here telling you how to do it for very good reasons.
2. Numbers look great and all but to be honest you will get the biggest increase and the most useful power out of your chip with a 600-800mhz bump
Its easy, it will be 24/7 stable and in a lot of cases will outperform a massive O/C 8 times out of ten depending on application. Here im talking about real world applications not so called "Benchmarking".
3.Its not all about the processor, spend time tuning, ram timings,dividers,fsb frequency,latency. All have there part to play, when you get it right it will fly.
You can spend months changing tweaking to chase that sweet spot.
It is one thing to point you in the right direction but when it comes to those frequencies the voltage levels can get high and beyond the safe max, and nobody is going to help someone cook a Rig.
Like tonkatuffmofo said "Numbers look great and all but to be honest you will get the biggest increase and the most useful power out of your chip with a 600-800mhz bump Its easy, it will be 24/7 stable and in a lot of cases will outperform a massive O/C 8 times out of ten."
I would set it up to run at 3.8-4ghz and leave it alone.
I have done some big overclocks and in the end it wasnt worth it, I ended up cooking 2 790I boards in the process just to get a high 3dmark06 score.
Since then I havent done it. Its not worth it.