What is the optimal QPI speed on an i7 860?

[Dougx1317]

I've got an i7 860, and I've tried 171x21 and 200x18. They're both at 3.6Ghz CPU clock with a QPI of about 3000Mhz vs 3600Mhz. Benchmarks I've run are non-conclusive. Do I want it faster or does it not make a difference? Or is there some RAM matching thing?

 

[cjl]

There isn't a RAM matching thing, and honestly, it shouldn't make any difference.

Oh, and the 860 doesn't have a QPI. What you're talking about is DMI, which connects to the controller for PCI, SATA, and any secondary PCI-E (not the ones for the graphics card).

 

[Dougx1317]

If there is no QPI, why does my bios have a QPI speed? I also just realized that the above speeds were the uncore speeds. The QPI was twice as fast, 6Ghz and 7.2Ghz. Does the uncore speed have any affect on performance? I know what both of these are in principle, I just don't know if I should worry about them when overclocking.

 

[warmon6]

If there is no QPI, why does my bios have a QPI speed? I also just realized that the above speeds were the uncore speeds. The QPI was twice as fast, 6Ghz and 7.2Ghz. Does the uncore speed have any affect on performance? I know what both of these are in principle, I just don't know if I should worry about them when overclocking.

Well i dont think we can explain why the motherboard has qpi but only i7 9xx's have it

http://www.intel.com/products/processor/corei7/specifications.htm

the only thing the i7 8xx's have is DMI's.

 

[Dougx1317]

Well, it must just be what they happen to call on this motherboard, I guess.

Should I worry about the QPI (DMI) speed or Uncore speed when overclocking? Do either effect performance.

 

[LePhuronn]

Because X58 chipset came out first and it uses QPI, it's entirely possible that the BIOS just uses the QPI name to save some confusion (and actually creating it in the process). As warmon6 says the P55 equivalent is DMI but in terms of user experience and how you manipulate it it's more or less the same thing. Certainly you treat it the same as you do QPI when you're overclocking.

 

[Scotteq]

Unless you have some specific need (i.e. a hugely memory bandwidth intensive program), it doesn't matter.

Use whichever setup runs with the best/lowest temperatures and voltages.

 

[archibael]

There isn't a RAM matching thing, and honestly, it shouldn't make any difference.

Oh, and the 860 doesn't have a QPI. What you're talking about is DMI, which connects to the controller for PCI, SATA, and any secondary PCI-E (not the ones for the graphics card).

Actually, the 860s have QPI, but it's internal to the silicon. I haven't played with any of the motherboards, so I was unaware the QPI frequency was accessible from there, though.