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Does Core i7 QPI Matter?

Last response: in Systems
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April 18, 2009 10:21:28 PM

I know this is an overrated topic about 920 (4.8GT/s), 940 (4.8GT/s), and 965 EE (6.4GT/s). I guess I can say no discussion between 920 and 940 about QPI. But I'm just wondering about the non-EE and EE. I understand that 920 can reach 3.2Ghz but does the QPI has a big factor in terms of performance and speed against 965?

After reading a lot about 940 i know now it's really not worth the price but I'm still curious why some people say 965 is also a lost cost. They said 965 is for benchmarkers, extreme overclockers, but is it seems unfair if they said it's also for people who don't know OCing. How about for people who only want a PC that has high speed and performance that will last a few years and not being weary of their CPU be obsolete quickly.


Thanks,

Roberto.

More about : core qpi matter

April 19, 2009 1:30:53 AM

QPI basically only dictates the maximum rate which data from RAM can get to the CPU. obiviously, faster is better, but then you are limited to what ram you have. frankly, the 920 seems best unless your pockets are fairly deep.
April 19, 2009 7:59:16 AM

Actually, that isn't the case. QPI is completely separate from RAM.

The QPI is the data link from the CPU to the northbridge, which connects it to hard drives, graphics cards, and the like.
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April 19, 2009 9:36:05 AM

Sorry to be thick. So does this means QPI is still a big factor to speed? Is that right? Do you think 965 QPI is worth it? Thanks.
April 19, 2009 10:23:56 AM

you can overclock the QPI, it goes up with the QPI base.
April 19, 2009 12:36:24 PM

The speed difference in most, if not all, application with 4.8 or 6.4 GT/s QPI is nearly non-existant. You can also very easily reach QPI 6.4 with the 920. The only advantage with the 965/975 is that the multiplier is unlocked, which gives you more option with your Overclocking. You could want lower BCLK and higher multi, or the contrary. It all plays on the stability of the OC. And so on.
April 19, 2009 2:04:01 PM

Sorry to be thick. So does this means QPI is still a big factor to overall system speed? Is that right? Do you think 965 QPI is worth it? What I'm actually wondering about is that even if you manage to overclock 920 with the same speed as 965 will there be a bottleneck between CPU and the northbridge due to the QPI?

Please correct me if I'm wrong but the way I understand QPI is that it's like a road (connection to northbridge). 965 is probably a dual (or 1 1/2 for that matter) carriage and 924/940 is a single carriage and data is the car. If the amount of car is less than the carriage then there will be a traffic. So even if you have a 920@3.2 the amount of data flowing is not enough to accomodate it. Can you please correct my analogy?

Thanks.
April 19, 2009 8:13:08 PM

You are way wrong. Whether or not you OC your 920 @ 3.2, you can OC the QPI to 6.4. But you will never see any real life difference in applications and gameplay. Maybe a bit of a difference in Benchmark, that's about it.

Bottom of the question is, do you want to do extreme OC with Water or your want a mild OC with air? If you go with air go with the 920, if you go with water, and you have deep pockets, go for the 965, or wait for the 975 for that matter.

There is no bottleneck with any i7 processors. End of the question.
April 19, 2009 8:47:24 PM

Does all motherboard support this functionality? Is there a link for this? Thanks.
April 25, 2009 1:18:01 AM

I finally found a forum about this. according to it. Only Retail i7 920 & 940 has this capability (unlocked memory multiplier) and also most motherboard should give them option to adjust to 6.4 gt/s. My question now goes to people own D0 stepping. Did intel still keep this? Thanks.
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