P67 PCIe Slot Performance Comparison With OCZ Revodrive X2 Linus Tech Tips
Linus Tech Tips
·Linus Tech Tips
·2011-05-08
·
686 words · ~3 min read
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now as some of you may know uh Intel's
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p67 platform has only 16 PCI Express
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Lanes available for graphics configurations well basically available
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for your main two PCI E slots here I'm going to show you a board that doesn't
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have stuff installed on it so you've only got 16 PCI ex press
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lanes for this one and this one which means you can either do 16x and actually
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I think you can make it run at 1X so it might be 17 PCI Express lames not the
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point okay so it's either 16 X or 8X 8X
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on these two now some Sandy Bridge boards p67 boards that is have a third
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PCI Express 16x physical slot this isn't the only one but this is the ASUS
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p67 uh p8 p67 Deluxe and this one does
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have a third slot so because there's only 16 Lanes running off of the CPU
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itself for those graphics card slots
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where does this extra PCI e6x slot run off of well
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the answer is that this is actually only a PCIe 4X
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slot and it actually runs off of the
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chipset so there is an inherent delay
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now the chipset does get a fair bit of bandwidth to the CPU itself but that
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PCIe slot is actually not tied directly to the CPU the way that the other ones
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are so I had someone ask me a question
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what if you're running something like this like an ocz Revo Drive X2 to 40 gig
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I happen to have one handy is there a performance difference
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between running it off of a PCIe slot that's running off the CPU versus
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running it off a PCIe slot that's running off what is essentially in
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archaic terms the South Bridge so this video is an attempt to answer that I'm
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just going to be using Crystal disc Mark to keep things simple and so I'm running
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five uh five times the entire test I'm
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running it over a 4 gig span of the drive and here are my results running it
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in the in theory faster PCIe slot and
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now I'm going to run it in the other PCI slot and see what happens well it would
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appear that I have my answer the sequential numbers are oddly enough uh
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very very close for reads uh this is
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running off of the chipset PCI E slot
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and then the screenshot I have here on the left is running off of the CPU PCI
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Express slot so the sequential reads are pretty much Within margin of error the
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sequential rights look to be a little bit higher on the on the chipset PCI
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Express slot for whatever reason and then moving down into the random reads
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and wrs it looks like for reads we're pretty much within the margin of error
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but then for random rights for whatever reason actually well random reads here
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you know what overall random performance seems to be higher on the CPU PCI
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Express versus on the chipset PCI
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Express and that does seem to be like a noticeable overall trend um so yeah I'm
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not sure why that would be maybe it's to do with the latencies involved although
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storage latencies are usually
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um what I should say is uh is is chipset
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latencies are usually nothing compared to storage latencies uh so I I wouldn't
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have thought that it would affect it that much but it looks like uh for
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whatever reason the the uh the lower latency between the CPU and this PCI
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Express slot versus the CPU to that chipset to that PCI Express slot seems
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to give us slightly better performance in random reads both in a light workload
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scenario as well as in a heavy workload scenario so thank you for checking out
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this little Linus Tech tips video about
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the revo Drive X2 on the PC 67 chipset
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don't forget to subscribe for more unboxings reviews and other computer
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