i7 architechture question

[ebarone]

Is there any performance-impacting function of an i7 system thats tied directly to BCLK? As in... is there anything where theres NOT a user-editable multiplier and associated voltage? I ask because I have the 975X, and in wanting to OC it, do I need to mess with the BCLK or do all important functions of the system run at a speed multiplied off of that, which I can set?

Edited April 27, 2010 by ebarone

[Zertz]

I assume you mean like: 133x30 vs 200x20?

 

All else being the same, no it won't make a difference

[ebarone]

Sorta, yea... I dont just want to OC the processor, I want to maximize all aspects of system performance (dont we all?) and I guess I'm still stuck a little in the C2D mindset, where the FSB clock and the RAM were far more intertwined. Seems like on this though, each subsystem can be addressed independently through multipliers, which I'm guessing would allow me to run a lower BCLK and therefore lower volts on the clock generator... is that true?

[Zertz]

Well, if you run a lower BCLK you will also decrease the processor, memory, uncore and QPI clocks unless you have an unlocked Extreme Edition. The clock generator (PLL) probably draws so little power, that running 1.7V instead of the stock 1.8V won't save you any power anyway.

 

What you can do to maximize stock performance is tweak memory timings. Other than that, overclocking is the way to go!

[ebarone]

I do have the unlocked i7 975X, I just want to make sure I'm not just OC'ing the cores, but also every other aspect of the system (RAM, QPI, Uncore). I know the common OC method is to raise the BCLK since most people own 920s or 930s and cant raise the cpu multiplier, but everyone can raise the multipliers for the other three subsystems right? I remember one of the big performance gains I saw with my C2D was to lower the FSB slightly in order to tighten one specific RAM timing (tRD)... basically dealing with all those fun straps and whatnot. Now with this i7 rig, will I need to worry about that any? Can I simply pick a convenient number for the BCLK and just overclock using multipliers alone? Or are there strapping issues/ram timing issues/other issues that are tied to the actual frequency of BCLK?

[Zertz]

Ahhh, it's clearer now

 

When you increase the BCLK, every other clock follows because they're all tied to the BLCK. Fortunately, the FSB strap issue is now gone because the memory controller is integrated on the core.

 

Basically, yes, pick a convenient BCLK (133, 160 and 200 are good, but it mainly depends on your memory) and adjust your multipliers. Extreme editions are nice to work with since they're so flexible

[ebarone]

As sort of a follow-up to this thread, what voltages are associated with increasing clock speed? Basically, I'm getting the under-voltage BSODs, eg when I run Prime95 and can see that the temps are okay (never over 70) but after a little bit of Prime I get the BSOD. In the past thats always meant voltage. Is it JUST the vcore I should be changing when overclocking via multiplier, or is there something else that might be causing it? What exactly does Load Line Calibration do?

[ebarone]

Is load line calibration worthwhile to have enabled? If I'm losing stability under load, but temps are sub-60s, which voltages should I look to change, keeping in mind my method of OCing so far has been to simply set the BCLK to 160 and multiplier to 26, 27, 28,... ? Thanks!