4850 Crossfire bottlenecked by x8/x8 lanes

Looks like mainly at 2560x1600 resolutions you start seeing bottlenecks. 1280 x 1024 and 1920 x 1200 are almost neck and neck..

Definitely going X48 next time around though (if I go with CF that is, during my PC overhaul) since they're not that expensive
 
Correct. Seems like another one of those benchmarks where the only difference is at resolutions most of us don't use. The bottleneck is there, however. I'm thinking the difference might be more apparent on the 4870's.
 
I guess the cards are finally catching up to the bandwidth. Thanks for teh post and link, OP, this answers my question from the other thread of how (2) 4000 series cards would work in an older x8/x8 PCIx 1.0 spec on my 975x board.

Guess its single card for me.
 
Not that expensive? An X48 board is more than an HD4850. And I wouldn't call those Crysis results "neck and neck" at any resolution. I've got to hope that drivers will improve the CF performance on P45, because otherwise those results are really disappointing. Then again, P45 CF boards are overpriced anyway IMO. Spot check shows the cheapest one out is $130, and that for Biostar. $150 if you want an Asus or a Gigabyte. At those prices, yeah I guess you might as well go X48.

Any which way you slice it, it sounds like waiting for a 4870x2 is a much better proposition.
 
Kluden said:
I guess the cards are finally catching up to the bandwidth. Thanks for teh post and link, OP
Click to expand...
^ Nice to see the cards are using the full bandwidth, I will keep this in mind when I build towards the end of the summer.
 
i seldom trust anything from the tweaktown articles. i'll wait until i've got these cars in hand before passing judgment on p45.
 
Well if PCIE 2.0 x8 lanes are equivalent to PCIE 1.0 x16 lanes, then is that article suggesting that regular x16 will be bottlenecked as well? I find that part a little hard to believe, unless my knowledge of the relation between 2.0 and 1.0/1.1 is wrong.
 
In some games the x8/x8 performance was better.....interesting. I don't think the difference will kill me at 16x10. I have a DFI 975x
 
Kluden said:
I guess the cards are finally catching up to the bandwidth. Thanks for teh post and link, OP, this answers my question from the other thread of how (2) 4000 series cards would work in an older x8/x8 PCIx 1.0 spec on my 975x board.

Guess its single card for me.
Click to expand...

four years after its introduction, pci-e 1.1 ran outta juice.

pci-e 2.0 will be killed within the year. I've said it before and I'll say it again, you can't double the supply and expect it to last when the deman is growing (literally) exponentially.
 
I guess this is the time to say "AGP IS DEAD" :D Hopefully there won't be any HD4850 AGP :p
 
If 2 4850s max out PCIe 2.0 @ 8x slots, shouldn't 2 4870x2s max out PCIe 2.0 @16x slots? I want to see some more testing...
 
ND40oz said:
If 2 4850s max out PCIe 2.0 @ 8x slots, shouldn't 2 4870x2s max out PCIe 2.0 @16x slots? I want to see some more testing...
Click to expand...

So do I. I won't be getting X2's, but I'd be curious how much further PCIE 2.0 can go.
 
PCIE 3.0 is due in 2009 it seems so PCIE2.0 getting maxed out soon might be possible. But I always thought the myth was PCIE 1.1 was never really threatened. I guess all these big video cards recently have done it though
 
pci-e 3.0 is even dumber than pci-e 2.0 if the numbers are infact 8Gbits/sec. pci-e 3.0 will work for one generation of cards, and hinder the next. No, radical changes, like that of the move from agp to pci-e, are going to be needed for a standard thats as long lasting as pci-e 1.1 was; somewhere on the order of 1000Gbits/sec would be ok. Rest assured whatever thats called wont be backwards compatable and will put nehalems quick-path to shame.

ZerazaX said:
PCIE 3.0 is due in 2009 it seems so PCIE2.0 getting maxed out soon might be possible. But I always thought the myth was PCIE 1.1 was never really threatened. I guess all these big video cards recently have done it though
Click to expand...

First version of DOS, 640KB. That was huge at the time, so huge infact gates said that no person would never need more than 640K of memory. Ever. When the 32bit Kernal came along the cap was raised to 4GB. Bill kept his mouth shut this time, but many people were thinking we were never going to run out of memory addresses, I mean 4GB? thats huge! We just hit it, which is why the 64bit desktop operating system was born (thankfully the servers hit it before us so by the time the consumer wanted a 64bit OS the idea was already well developed). Well, with our newly found 64bit operating systems, and their cap of 18 Exabytes (18 billion gigabytes), I'll go ahead and say it: "we're never going to need that much memory!!"

I'm betting it'l be less than a decade before thats prooven wrong. What then, the 128 bit OS? thats 316 billion billion billion gigabytes. I shudder to think of the 256bit operating system.

My only point is computers really are the fastest growing industry in the world, and remember its only really 20 years old. So saying "i'll never need to upgrade" means you've got a maximum of 4 years until you need to upgrade. Except (I hope) with 1KW psus.
 
I think I can say with some certainty that 18exabytes will never be reached by silicon.

We have 1TB (hd, forget ram) now, 1000 of those is 1 petabyte, then 1000 of those is 1 exabyte. Try and find a use for that I dare you. Even superduperuber HD won't fill that. We'll need virtual reality simulations to get there, and I doubt we can do that without optical/quantum/biological computing.

I never said we won't need it mind you, I'm just saying our current technology won't get there even with 3d chips...
 
This was a concern of mine with my p5k-e, it is 16x/4x, thus no crossfire for the 4850, guess I wait till the 4870 comes out and just do a single card solution.
 
I don't trust tweaktown, but those numbers have me changing my mind about P45 being a good combo with dual 4850's... I want another site that I trust to do a review damnit!
 
F.E.A.R. said:
In some games the x8/x8 performance was better.....interesting. I don't think the difference will kill me at 16x10. I have a DFI 975x
Click to expand...

Margine of error. So many people take these numbers so literally. The softwares never going to get it perfect. It samples the cards output several times a second which is plent of room for it not to catch something. Whenever you see a review, if two cards are withen 5% of each other, they're identical.
 
Can anyone de-confuse me? I have been hearing all over the place that the two 8x lanes on the P45 motherboards were just as good as dual 16x because it is PCIe 2.0... Is this not true?
 
MaStaFLaSH said:
I don't trust tweaktown, but those numbers have me changing my mind about P45 being a good combo with dual 4850's... I want another site that I trust to do a review damnit!
Click to expand...

techpriest said:
why are people not trusting tweaktown? Just curious
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I was thinking they're seeming suspiciously excited about a card that performs just as well as another $250 card, the 9800GTX. Then I realized they're based in austrailia where (by there own words), an HD4850 will cost $250, where the 9800GTX currently goes for around $350.
 
wait a minitue, isn't there alot of crosstalk between the cards in xfire versus a single card or a x2 where they can talk directly to each other?
 
Romale23 said:
wait a minitue, isn't there alot of crosstalk between the cards in xfire versus a single card or a x2 where they can talk directly to each other?
Click to expand...

lol.

the only form of foreign bus in the RV770's syntax is a pci-e (2.0?) bus, as such they have to give each chip on the HD3870X2 a pci-e bus, so the ALX bridge simply takes the 16 coming to it off the connector and splits it between the two chips. The cant talk to each other any more effectivly than two cards each connected over the Northbridge in traditional crossfire fashion. That said, ATI would argue that their method of com over the northbridge is more effective than Nvidias combine NB, SB approach.
 
Ok i've heard so many different things now. I really hope I didn't spend $200 on a P5Q-D just so I get bottlenecked in Crossfire withe 2 HD4780s or X2s.
 
so yeah i just bought a Abit Quad GT X38 motherboard to replace my IP35 Pro. Noticing some slowdown in COD 4 and Company of Heroes with only 4xaa at 1680x1050, like dips into the 20fps in COD4. Will see if this fixes the issue next week.

and ricochet48, ive read 2 sites that say p45 is not the best idea for crossfire, best to go with 2 full fledged 16x lanes.
 
I just pulled the trigger on my new system, including a P5Q PRO (P45) and 4850, with intentions to eventually grab another for some CF action. Looks like this was not the best choice ;/
 
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