WEBVTT

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all right i'm going to take another crack at my PCIe 16x versus 8x versus 4x

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testing this time i'm going to use a couple of games that i've benchmarked

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quite a bit in the past we're going to go with battlefield bad company 2 as

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well as metro 2033 since i had people

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asking for not a purely synthetic test so i'm going to use the 69 90 again

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single card gonna run at 16x 8x and 4x

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PCIe bandwidth and see what kind of performance differences we see at 1080p

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running in these games

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so this was interesting uh not only did i test battlefield bad company 2 and

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metro 2033 actually i've got my fraps one of my fraps results up here

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right now oh apparently i have a lot of them up here right now okay so i also

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added crisis 2 to the testing

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methodology so here you go here are my results in a very tiny little graph that

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i have made on a piece of paper along with a list of stuff that i had to do

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the other day okay so here we are oh please focus come on you'll be kidding

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me focus

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focus there we go yeah yeah

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okay so crisis two from 16x to 8x we're looking at pretty

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much within margin of error but then as soon as we drop down to 4x PCIe

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bandwidth we lose about six to well six

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to eight FPS so that's going to be about 10 so we do see a tangible real world

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performance decrease on a very high performance card in crisis 2 going down

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to 4x that'll feel bad company 2 once again we see kind of within the margin

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of error and then as soon as we go down to 4x we

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see a very dramatic decrease in performance about 30

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so metro 2033 same story this is margin of error right here and then moving down

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to 4x we see a yeah 12-ish percent

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performance drop so basically this goes

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against the findings that i found before and i believe i know the reason so

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running the extreme preset on 3d mark 11 basically meant that the

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processors on the Radeon 6990 were completely taxed

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so we were creating a processor bottleneck which meant that there didn't

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have to be as much communication between the card and the rest of the system

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because we weren't able to actually we were we were limited by how much

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rendering these cores could do rather than by how quickly the card could

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communicate with the system so running at 1080p with some modern games we were

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able to create a scenario whereby the

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card was not actually the bottleneck in the performance of the system in that

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particular game so the processors were able to do more than the pci express

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bandwidth was capable of communicating

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so basically what we see here then

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is that as soon as PCIe 3.0 comes out

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we're probably looking at a scenario remember pci express is doubling in

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bandwidth every time we see a new iteration but we're probably looking at a scenario where any modern card will

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perform about like this at PCIe 3.0

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4x and will perform about like this at PCIe PCIe 3.08 x and then there will be

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a hypothetical probably like incremental 0.2 FPS beyond that so for any modern

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card and remember this is two modern high-end gpus those are each 6970s on

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there for any two modern high-end gpus

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PCIe 8x is pretty much enough and 16x is

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definitely enough based on how little improvement we see by doubling the

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bandwidth from a PCIe 8x slot to a 16x slot so thank you for checking out this

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episode of Linus tech tips don't forget to subscribe for more unboxings reviews

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and other computer videos