P45 Crossfire Performance

[Mad1723]

Here's a little peak at the performance of the P45 when in Crossfire situation. It shows really well the advantage of the P45 over the P35 in Crysis

French website, but the graphs speak for themselves!

[HKPolice]

No X38 = useless comparison.

[vengance_01]

I agree. We knew it would beat the P35 just from the fact that the P35 has a 16/4 and the P45 has an 8/8 config.

[STaRGaZeR]

I agree. We knew it would beat the P35 just from the fact that the P35 has a 16/4 and the P45 has an 8/8 config.

Remember, P35 is 16/4 PCIe 1.1 while P45 is 8/8 PCIe 2.0

[Frank M]

No X38 = useless comparison.

Ici, pour le CrossFire, c'est la libération. Il sera d'ailleurs INtéressant de voir si l'on constate une différence entre le P45 et le X48, qui dispose de deux fois plus de lignes par port, lors de nos prochains essais.

P45 - X48 comparison in their upcoming article.


Do I see that right, that a single card does better than crossfire?
Am I missing something? (I didn't read the whole review, just this page)

[Mad1723]

There's probably a problem with HD3870 Crossfire on their platform. They used Cat 8.5 though... there shouldn't be any problems... I don't know what caused that weird fact O_o

[MpG]

Hard to say for certain, but it seems they're using 256MB cards. It wouldn't be too hard for their settings to be high enough to fill the cards' video memory, which brings system memory into the equation (in both single and Xfire setup). But since XFire duplicates the video memory across each card, it has twice as much info moving between the video and system memory, possibly to the point where performance actually gets worse. And it's not like Crysis is a multi-GPU wonder to begin with, of course.

If true, that there's an excessive amount of a video/system data exchange, this would translate into a much higher level of PCI-E traffic. In which case, x8 (v2.0) lanes would be a HUGE advantage over x4 (v1.1) lanes. Hence, the P45's considerable improvement over the P35, even in single-card setup.

I'd be willing to bet that 512MB versions of the ATI cards wouldn't show nearly as much difference. And likewise, the 512MB Nvidia card probably has enough video memory, negating a lot of the P45's PCI-E 2.0 advantage, and resulting in nearly identical benchmark performance across both platforms.

Well, that's my guess, anyway.

[Polizei]

Remember, P35 is 16/4 PCIe 1.1 while P45 is 8/8 PCIe 2.0

I'm pretty sure the only difference between PCI-E 1.1 and PCI-E 2.0 is that 2.0 can deliver more power to the card via the slot than 1.1. No difference in slot bandwidth.

[Spectrobozo]

I'm pretty sure the only difference between PCI-E 1.1 and PCI-E 2.0 is that 2.0 can deliver more power to the card via the slot than 1.1. No difference in slot bandwidth.

it's more than just more power,
http://www.anandtech.com/cpuchipsets...spx?i=3192&p=2

[wyemarn]

since 2.0 have twice bandwith of 1.x per lane, bandwith wise x8 2.0 = x16 1.x, i dont think running crossfire in p45 will be bottlenecked by PCI-E bandwith.

[Mungri]

The difference between 2x 8x PCI-E 1.1 and 2x 16x PCI-E 2.0 was zilch, zero, nothing.

There was a review somewhere comparing an MSI P35 with 16x/4x, Asus P35 with 8x/8x, and an X48 with 16x/16x and there was no difference between the last two. I only got an X48 due to impatience, but graphics performance on the P45 shouldnt be any different to X48. The only difference will be the price tag, and overclock ability.

[WhiteFireDragon]

ah so pretty much wen p45 comes out, x48 will not have XFire advantage anymore?

[tekjunkie]

The difference between 2x 8x PCI-E 1.1 and 2x 16x PCI-E 2.0 was zilch, zero, nothing.

There was a review somewhere comparing an MSI P35 with 16x/4x, Asus P35 with 8x/8x, and an X48 with 16x/16x and there was no difference between the last two. I only got an X48 due to impatience, but graphics performance on the P45 shouldnt be any different to X48. The only difference will be the price tag, and overclock ability.

Add to that less heat coz of the NB die shrink

[[XC] gomeler]

CrossFire works perfectly fine on P45. I used 2 HD3870's and toyed with nearly 100k 3D01 at near stock clocks and 5.4GHz CPU. You won't have bandwidth restrictions until you start using 3 PCIe slots and dropping to 8x/4x/4x in which case the 4x might impact performance slightly. P45 might include a die shrink but the heat doesn't seem much different from P35, perhaps P35 was just cool running to start. X48 will still be my platform of choice for X2 cards, otherwise for most users there won't be a difference.

[ghost101]

So in crossfire

P35 has 16x/4x pci-e 1.1 lanes
p45 has 8x/8x pci-e 2.0 lanes
x38 has 16x/16x pci-e 2.0 lanes
x48 = x38

So p45 wont be any better than x38/x48 boards.

[strange|ife]

I see a P45 in my future for the right price.

[STaRGaZeR]

I'm pretty sure the only difference between PCI-E 1.1 and PCI-E 2.0 is that 2.0 can deliver more power to the card via the slot than 1.1. No difference in slot bandwidth.

As others have already said, there is a difference in both bandwidth and power delivering. 16x 2.0 = 32x 1.1 (hypotetically, there is no physical 32 lanes conection yet), 8x 2.0 = 16x 1.1, 4x 2.0 = 8x 1.1, etc. So with P45 you have a traditional 16/16 PCIe 1.1 configuration, which is more than enough and will not cause any bottleneck.

[Hawkeye4077]

I see a P45 in my future for the right price.

Same here! That and a couple 3870s in CF and ill be a happy camper

Time to buy some more tubing for my loop!!

[Mungri]

Add to that less heat coz of the NB die shrink

Not necessarilly. MSI stated, I think on hexus, but not 100% sure where I read it, that the reason the P45 needed much better cooling was because it runs around 10 degrees hotter then the P45. I have had big doubts about the P45 which pushed me further to getting the X48.

Time will tell how well it does with overclocking, but as far as graphics are concerned, IMO by the time cards are so powerful that they actually need the bandwidth of PCI-E 2.0 16x/16x, we will already have PCI-E 3 released. An 8x/8x combination still provides all the bandwidth that current cards require. Its like how putting a 512 bit memory interface on ATI cards makes virtually no difference over 256 bit, also, a 500 Mhz ram overclock on my 3850's (I tested at 1600 and 2100 Mhz) only gives a difference of around 300 points in 3D mark 06, but GPU overclocks scale much more higher then the ram

Bandwidth is currently too far ahead and bottlenecked by current GPU's, and once we have faster cards in a few years time, the current bandwidth we have will be plenty for them lol.

Bandwidth = overrated. Its the same as the difference between DDR2 and DDR3 system memory in terms of performance.

[FischOderAal]

So in crossfire

P35 has 16x/4x pci-e 1.1 lanes
p45 has 8x/8x pci-e 2.0 lanes
x38 has 16x/16x pci-e 2.0 lanes
x48 = x38

So p45 wont be any better than x38/x48 boards.

Why should P45 be better than X38/X48? P45 = mainstream, X48 = Highend!

P45 might be a better choice though, due to smaller structures and the double bandwith isn't needed by the graphic cards.

Not necessarilly. MSI stated, I think on hexus, but not 100% sure where I read it, that the reason the P45 needed much better cooling was because it runs around 10 degrees hotter then the P35. I have had big doubts about the P45 which pushed me further to getting the X48.

fixed and why does it run hotter? maybe the heatspreader causes this.

[Gambit_2K]

Why should P45 be better than X38/X48? P45 = mainstream, X48 = Highend!

P45 might be a better choice though, due to smaller structures and the double bandwith isn't needed by the graphic cards.



fixed and why does it run hotter? maybe the heatspreader causes this.

Hmm the P35 klocked better then X38 and X48 so mainstream chipset could be called higher end in some cases.