A little overclocking adventure and some questions

I overclocked my Phenom II X3 720BE over the weekend to 3.3GHz by increasing the multiplier only. Ran Prime95 for around an hour (I know this is a relatively short time) and all seemed stable. However, whilst downloading a game using EA Download Manager I received a BSOD and have now restored the multiplier back to auto. This was my first attempt to overclock.

From my limited testing previously it looks like I'm lucky enough to have a chip that can be unlocked to a quad core, but I lose the CPU core temperature monitor and according to HWMonitor the TDP raises from 99W to 130W, which I'm not keen on. I look at core-unlocking as something I can do in the future if I need it. :)

This, admittedly, short adventure, has lead me to some questions though. :)

1. Would I need to increase any voltages to obtain a reliable overclock? What is the difference between CPU Voltage and CPU-NB voltage?
2. If I increase the voltage of the CPU, does the cool 'n' quiet function still work and ramp the voltage down with the multiplier when idling? I know the multiplier ramps down, just not sure about the voltage.
3. Does the fact that I am using 4 RAM modules affect my overclocking ability? Would I need to increase voltage to the modules or NB? I have read that early Phenom II's have issues with 4 DIMMs installed and that I should relax the speed back to 1066MHz?

Generally, my system runs pretty cool (at stock, the CPU idles at about 25 degrees and at load reaches about 43 degrees). Even with the overclock to 3.3GHz it was still only reaching 47 degrees at load.

My system specs are up-to-date on the left, and I have a nice Enzotech copper heatsink mounted on the motherboard VRMs, which should help overclocking.

Has anybody embarked on an AMD Black Edition overclocking adventure and got any tips or answers to the above?

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Originally Posted by barry2811

1. Would I need to increase any voltages to obtain a reliable overclock? What is the difference between CPU Voltage and CPU-NB voltage?
2. If I increase the voltage of the CPU, does the cool 'n' quiet function still work and ramp the voltage down with the multiplier when idling? I know the multiplier ramps down, just not sure about the voltage.
3. Does the fact that I am using 4 RAM modules affect my overclocking ability? Would I need to increase voltage to the modules or NB? I have read that early Phenom II's have issues with 4 DIMMs installed and that I should relax the speed back to 1066MHz?

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1. Yes. The CPU Voltage is for the CPU (obviously), the CPU-NB voltage is for the North Bridge (i.e. the chipset). Most often it's only necessary to increase the CPU Voltage, unless you take up some extreme overclocking. But with a BE CPU you don't overclock the bus (FSB/HT, etc.), so increasing the NB voltage isn't necessary.
2. It still works, but the increased voltage stays in both load and idle (i.e. if you idle voltage was 0.8V, with increased voltage it might be 0.825V, 0.85V, etc.). Edit: I've remembered now, that by changing the multiplier from Auto to some fixed one in BIOS you lose C'n'Q. Though, if you change it through some overclocking utility (e.g. AMD Overdrive), you might retain C'n'Q. Correct me if I'm wrong :)
3. It might be, but again, since you're only increasing the multiplier of the CPU, other components aren't stressed by overclocking this way.

As for core unlocking: on my previous Phenom II X3 720 BE I've successfully unlocked the core and ran it with 4 cores and lower voltage at the same time with no consequences except for higher temperatures. But have in mind, increasing the voltage will also increase the TDP as well, so you might weigh in what you need more: higher frequency or the fourth core.

Check out the dependency of the temperatures on the CPU Voltage here, I've done some tinkering with my previous 720: http://forums.hexus.net/hexus-hardwa...adventure.html

Hope that clears things up a bit :)

Thanks for the response. I've had another look and I'm now running at 3.5GHz with 1.4V to the CPU.

Cool 'n' quiet still works ok and the CPU still idles at 800MHz and 1.08V. From what I've read the way cool 'n' quiet behaves when overclocking depends on the motherboard. It looks like my board takes the overclocked settings and uses them for the highest power state, preserving the stock settings for lower states, which is a nice bonus as far as I'm concerned. :)

I believe C&Q settings and stability under non-stock running does vary from board to board. My ASUS 785G board happily allows C&Q operation even when heavily undervolted, so I'm currently running my Sempron @ -0.3v from stock, which translates to 0.77v when idle ;) As usual, YMMV.