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need expert help in new compouter questions

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  • Crossfire
  • CPUs
Last response: in CPUs
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August 19, 2014 10:10:22 PM

hi, im squarly focusing primarily on the number of pcie bus lanes because im thinking of upgrading from my i7 920 and waiting till hasweel -e comes out.

my deciding factors arew I know for a fact I will be using 3-way crossfire and on all chipsets up intilo the haswell -e ud only get x8/x4/x4 lanes on the graphics. so vs x16/x8/x8 I think there might be a huge benefit to having this in cpu i98ntesive games and for 3-way crossfire in general.

my question is how much a noticeable difference would there be?

I cant help but think about the problem with crossfire cinfigurations years agoi with diminishing returns when you add a second card and more so when you have 3cards. I am wondering if the reason for these dimishing returns is the lower PCI-E bus and weather or not the thought of diminishing returns will be a thing of the past now with more pci-e lanes

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August 19, 2014 11:38:55 PM

The diminishing returns have very little to do with PCIe lanes, unfortunately. The problem is that it's extremely difficult to split the work evenly between GPUs. It basically involves trying to guess how much work will be involved and splitting it evenly, but there's no accurate way to predict how much work will be involved. You might give alternative frames to each GPU, but one frame may involve much more processing work than the next. However it's done, you'll almost always end up with the cards waiting for one another.

We've seen from past driver releases that writing a driver specifically for a game can have a major impact on scaling and improve performance. However, 2 card Crossfire setups are already niche, 3 & 4 card setups are extremely rare. When you have limited resources to devote to driver development, you're hardly going to allocate them to resolving issues for a tiny fraction of your market.

3 way setups are really not a great idea IMHO. You'll only see benefits in a small number of games and for other games it will actually introduce issues (stutter/lag/inconsistent frame rates). By all means if you have a massive budget and are prepared to put the time in to test the scaling and check for inconsistent frame rates when new games come out, go for it. But you should be aware that you're putting a lot of $$s into something that will only work for some games and will actually make things worse for others.
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August 24, 2014 8:37:15 PM

Well I already have one 280x and was moving to quad HD 4k although trifire latency makes me wonder if that be a problem
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