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Ques. About Data Transfer Between GPU & MoBo

Last response: in Graphics & Displays
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April 5, 2011 1:01:18 AM

Those that roam about may have come across this from me before, but I wanna know, how do you figure out what the speed of the Video Card is, when it is transferring data to and from the MoBo via the PCI Slot? How is it rated?
a b U Graphics card
April 5, 2011 1:06:50 AM

That's... a good question actually.

I honestly don't know.
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April 5, 2011 1:51:21 AM

Well I know Everest should be able to tell you at least something similar, but I meant in how (lol) can you figure it out from a GPU's Specs?
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a c 202 U Graphics card
April 5, 2011 1:55:39 AM

Look at the version of PCI-E that the card is and the version that the motherboard is, the lowest version of the two will take precedence, then see if its in a slot rated for 16x or 8x. PCI-E 1.x is rated at 250MB/s per lane, PCI-E 2.x is 500 MB/s per lane, so a 16x PCI-E 1.x slot will have a bandwidth of 4 GB/s, a 2.x slot will have a bandwidth of 8 GB/s, that will tell you the max transfer speed, but rarely will it ever come close to saturating that bandwidth.
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a c 194 U Graphics card
April 5, 2011 3:51:31 AM

It sends 50x128mb of data from memory to the card and then card back to memory. I dont see how this doesnt show the bandwidth the card is using.
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April 5, 2011 5:39:41 AM

When I say, "figure out", I don't exactly mean running any tests, because I don't have the card as yet, it's on it's way from the USA right now.

There's a ton of different info for a GPU Specifications, so I was wondering if cards are rated at a certain speed when transferring data through the PCI-e slot. I don't see how you can't measure it as Dadiggle says, obviously it won't be a constant figure, but there must be like a range or something, so I can roughly compare it to the max speed a PCI-e slot supports.

If it really just isn't something that is listed with a GPU's specs, then I guess k1114 would have answered the question then.

~Des
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a c 202 U Graphics card
April 5, 2011 8:28:23 PM

Its a data bus, its going to have an incredibly variable amount of data on it at any given time, it might have absolutely nothing on it(or very close) when its sitting idle at the windows desktop and nothing is changing, or it might have a few GB/s of data flowing down it when you start up a game and it has to load up all the textures. Any individual measurement would be pretty meaningless, you would need to watch it over time but in order to watch it you would end up adding more overhead and processing to it which would affect the latency and throughput thus invalidating your results. Its a databus, it works and does its job, treat it like a magically highway because in reality you dont need to know how much traffic is on there, it really doesnt matter.
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April 5, 2011 9:09:00 PM

I understand that, that's why I was asking if there is something like a range. But okay, so, again, and for the last time, and let me ask it this way instead; there is no info available on Video Cards that states the max speed it will utilize when transferring data through the PCI-e Slot, WITHOUT doing any testing? God I hope i'm not sounding redundant...

~Des
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a c 194 U Graphics card
April 5, 2011 9:32:22 PM

No, you cannot find out the card's pcie bandwidth usage stated anywhere.
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