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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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