Intel Core i7 "Nehalem" 920, 940 & 965 XE Processor Review

by MAC     |     November 3, 2008

Feature Test: Goodbye FSB – Hello QPI



As mentioned previously, the QuickPath Interconnect (QPI) is the brand new high-speed interface that has replaced the decade-old front side bus. We are all familiar with the good 'ol FSB, and we also know that increasing it generally provides improved performance. Therefore, we were interested in determining whether there is a noticeable performance difference between a 4.8GT/s - 2400Mhz QPI Link and a 6.4GT/s - 3200Mhz QPI Link.

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To isolate the QuickPath Interconnect as the focus of the test, we downclocked our Core i7-965 to 2.66Ghz, and manually adjusted the the QPI speed option in the BIOS. Are consumers missing out by buying the lower-end Core i7-920 and 940 models? Let's find out!

Intel Core i7-965 @ 2.66Ghz - 4.8GT/s QPIIntel Core i7-965 @ 2.66Ghz - 6.4GT/s QPIPerformance Difference
3DMark Vantage: CPU Score1654016480Insignificant
Valve Particle Simulation Benchmark130130None
Cinebench R10 1-CPU35843571Insignificant
Cinebench R10 Multi-CPU1574515820Insignificant
x264 HD Benchmark22.8722.87None
WinRAR 3.71 Compression3:043:00Insignificant
SuperPI 1M15.641s15.625sInsignificant
SuperPI 32M14:05.465s14:04.715sInsignificant


The results certainly speak for themselves, a faster QPI Link does not increase overall performance....at least in our tests. It is quite possible that under a specific workload the faster QPI speed would in fact distinguish itself, however we suspect that this type of workload would only be found in the high-end workstation or server sector. It is also quite possible that even the 4.8GT/s QPI Link provides more than enough bandwidth for any possible workload.

Although we may have raised more questions than answers, it is clear the those who buy the lower-end Core i7 models and overclock them to Extreme Edition speeds will not be bottlenecked in any discernable manner.
 
 
 

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