PCI Express And CrossFire Scaling: Is P55 Good Enough?

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[citation][nom]a4mula[/nom]The only real question that hasn't been seen is the quadfire 5970's and a trifire 5970+5870. Publish that and you'll garner my attention at least.[/citation]

[citation][nom]gellert[/nom]Yeaaaaah! I've been waiting for this article for quite a while now, this clears up a lot of speculation! I hope you guys do a follow-up article to test whether two 8x,8x are enough to support 2x 5970's.[/citation]

Tom's is trying to locate a pair, but supplies are short. Tom's WILL keep trying!
 
[citation][nom]JackNaylorPE[/nom]Huh ?"We still haven’t seen how an X58 motherboard with x16/x16/x4 slots compares to today’s x16/x8/x8 sample"Reading this literally, the article compared two cards in 16x8 with 2 cards in 8x8. Was that an answer anyone was looking for ? Isn't the real question 16x16 compared with 8x8 ?'s an answer I didn't need to know.[/citation]

Read it LITTERALLY then apply the other board. The X58 board does x16/x16 or x16/x8/x8. As for comparing x16/x16 to x8/18, the P55 that x16, or x8/x8, or x8/x8/x4 with the x4 at 1.1 speed
 
[citation][nom]hixbot[/nom]^ i thought the point is to show 2 cards in x16 and x16 with two cards in x16 and x8.also i'm seeing many enthusiast p55 boards that claim two x16 PCI-e slots, whats up with that?[/citation]

Same comment, I should have grouped them. The x58 board here has two x16 lane sets and a set of switches as noted elsewhere in the article, so it does x16/x16 or x16/x8/x8 depending on how many cards are installed. And don't read specs from a manufacturer or seller, because they never tell you the whole story. You need to read reviews to figure out that the X58 has 36 lanes while the P55 has 16 on-die plus 8 slow ones on the chipset operating at x4 combined bandwidth due to the slower DMI connection from the CPU to the chipset.
 
[citation][nom]a4mula[/nom]It's going to benchmark the same, if not slower. The NF200 was deceiving on the Nvidia and x58 boards. It made it out to sound as if it created new pcie lanes out of thin air. That was never the case. All it did was reroute lanes. The x58 had the advantage of having 48 natural lanes to work with. The p55 on the other hand is limited to 16 lanes to the die. There is no add-on card that will magically gift you more access to the cpu on die gpu controller. http://www.bit-tech.net/hardware/m [...] 780i_sli/1They advertise 16x/8x/8x with nf200. While that might be electrically true, it's never going to result in performance gains because of the 2gb/s dmi speed.[/citation]

The X58 has 36 lanes. The NF200 does not rely on the chipsets lanes so the DMI limit doesn't apply but the CPU limit still applies
 
The next main issue will be of course how FERMI is handled across the various PCIe lanes. As recent reports suggest that they will run extremely hot (at least at pre release specs) I wonder what power they will draw and how the P55 chipset will handle them.

It would be a major booboo by nVidia if they suffered significant differences in performance between x16/x16 and x8/x8.
 
[citation][nom]hixbot[/nom]^ i thought the point is to show 2 cards in x16 and x16 with two cards in x16 and x8.also i'm seeing many enthusiast p55 boards that claim two x16 PCI-e slots, whats up with that?[/citation]

They are both x16 slots. But if you use them simultaneously (Crossfire or SLI) they both are forced to drop down to x8. The chipset/CPU combo of P55 & i5/i7 dictate a bandwidth limit of x16. So although a P55 board could theoretically have two slots which are both capable of x16, the system itself is only capable of a total of x16. So both slots drop to x8/x8 in order to run both cards.
 
Looks like the performance difference between having two 8x PCI-E 2.0 slots vs two 16x PCI-E 2.0 slots is becoming more evident with more powerful cards. Even so an LGA1156 based system is still a good cost effective basis for a dual GPU system that is using two 5850s or below. The i7 860 is a better choice than the 870 tho, and for using two powerful cards like the 5870, or three cards, it doesn't make sense to use a P55 system. Perhaps a P55 board augmented with a nf200 chip would change the picture a little.
 
One thing the author glossed over, rather inappropriately, is the x58 is degraded because it's only running two memory channels. It's only mentioned in passing.

Now, it's fine for a purely intellectual conversation about how much degradation you suffer using the P55, but in real life, the differences between even his slow x58 and fast P55 would be much greater, since you'd be using the extra memory channel in all probability. Also keep in mind the more you stress the system, the bigger the difference. The compromised design of the Lynnfield requires it to multiplex memory accesses between the video card and processors, since PCIe is on the processor. So, you'll get conflicts there that could lower performance slightly.

The P55 looks like something made by a marketing team and by bean counters, with plenty of compromises. The x58 looks like something made by the engineers. It's what they wanted to make.
 
[citation][nom]ohreally[/nom]If you are building a new rig right now and want it to last 2-3 years, make sure it has 16x16x lanes[/citation]

I'm curious as to what game you expect to come out in the next 2 years that will give a 5970 trouble. Currently, everything being produced by the gaming industry is set to run on PS3/360 level hardware, 3 generations behind, and that won't change until next gen consoles come out, 2014 at the earliest.

This is a huge issue for GPU makers, as the discrepancy btwn console and PC hardware increases. Major game makers refuse to create games that are PC exclusive, or if they do, like blizzard, are games that will run on 6 year old hardware.

Even Crysis 2 is being made to run on 360 and ps3.

Also, in less than 2 years Sandy Bridge CPU's + 22nm sockets will be out, so any board you buy today will be outdated by then regardless of PCIE bandwidth.

So at the end of the day, you're better off saving your ~$200 dollars and go with P55 and i5-750 for gaming, and just get a 5970.

 
[citation][nom]ohreally[/nom]And they just proved it WAS an issue with 5970's. How much more of an issue do you think it will be with 6970's? Or 7970's?Fact facts, anyone who has 8x pci-e slots is going to require an upgrade to 16x within 2 years if they wish to remain at the top of the gaming fps.If you are building a new rig right now and want it to last 2-3 years, make sure it has 16x16x lanes[/citation]

In 3 ?? years you're still going to be on the X58 platform? P55 plus a single fermi/5970 or 5870 is damn smooth. In 2 years ya might replace the 5870's with a single (dual gpu?) 7970(?) etc.

Or if you're a rich guy, in 3 years, you're going to want to sport the latest 12 core/16nm/quad channel ddr 4/quad 32 lane PCIe 3.0/quantum blah blah blah. Because basically you're either rich, and pimping 3 monitors or some monster 234999 inch thing, or you've got 1 regular(ish) monitor and P55 is fine.

Honestly 1 PCIe 16x lane is enough looking at the steam hardware survey. Crossfire always sounds good and sexy, then you figure out the extra electricity, larger/new power supply, better case/airflow and double upgrade cycle, it's just better (cost effective) to step up on the single card. Maybe it's cost effective in the short term to use 2 mainstream slower cards, but that doesn't count electricity and it nullifies the 16x vs 8x argument for now, and in 3 years you can go 1 fast card.

That's just my 4 cents.
 
Am I reading this wrong? How can the P55 run at x16 SLI/Crossfire? I thought that was the whole point of this exercise - to see how big a performance hit you take with the x58 @ x16 vs. p55 @ x8.
 
It was a tough decision for me between the x58 i7-920 and the more modern p55 i7-860. In the end, the faster clock speed, better efficiency, more overclockability, and more features won over.

I run two 4890's in a x8 setup and probably don't lose more than 4 fps average vs. a x16 setup. Probably more than make up for it with the i7-860's higher clocks.
 
[citation][nom]ta152h[/nom]One thing the author glossed over, rather inappropriately, is the x58 is degraded because it's only running two memory channels. It's only mentioned in passing.[/citation]

It was mentioned in passing, which is appropriate because this is an examination of PCIe scaling issues. There's no other fair way to do it. The closest thing to "fair" with triple-channel would be to set the X58 up with 3MB and the P55 with 4MB, but then you'd be using different parts on the different platforms which still isn't fair. Fortunately, Tom's has determined in past articles that triple-channel doesn't help games by more than 1%.
 
Why P55 is waste of money?

For $100 difference you can get 1366 socket system with i920 in it which is way better deal. 1366 socket will get 6 and 8 core upgrades and P55 LGA1156 wont ever see it. A day you buy P55 it is obsolete.
 
Awesome Article. I always wondered if the built in PCI-E controller on the Lynnfields would make a big difference. I would like to see a built in PCI-E controller that can handle 32 lanes of PCI-E bandwidth. 16 total lanes is kinda limiting. For people who add in Raid controller cards for the P55 boards, it would be limiting because they could only run their graphics card at 8X. I think I read somewhere that for the SATA 6gb/s P55 boards, if you utilize the SATA 6gb/s ports, that will also drop the X16 graphics down to 8X and you won't be able to Cross Fire or SLI either.

X58 is where the real power is. If you want PCI-E bandwidth, then the EVGA Classified 4-Way is the way to go right now. They only downside is the northbridge gets so hot, you can cook a steak on it.

I've heard rumors about Intel's next chipset (might be X68). It's suppose to be a beast. PCI-E bandwidth up the ying yang. PCI-E 3.0 will on it. It' will support full SATA 6gb/s. Currently the P55 boards don't run SATA 6gb/s at their rated speed because of the integrated pci-e controller on the chips. But it's all rumors. I can't confirm any of it.
 
[citation][nom]lradunovic77[/nom]Why P55 is waste of money? For $100 difference you can get 1366 socket system with i920 in it which is way better deal. 1366 socket will get 6 and 8 core upgrades and P55 LGA1156 wont ever see it. A day you buy P55 it is obsolete.[/citation]
I've not heard of anyone upgrading a CPU in an existing motherboard since Socket A. So it essentially doesn't matter if you can replace your expensive i7-920 with a better one later and not your cheaper i5 one.
Think of the $100 price difference as a 50% price increase over the baseline system - the system which doesn't perform anywhere that much worse AND uses less power but with more turbo (ie. non overclockers get quality too)
 
[citation][nom]lradunovic77[/nom]Why P55 is waste of money? For $100 difference you can get 1366 socket system with i920 in it which is way better deal. 1366 socket will get 6 and 8 core upgrades and P55 LGA1156 wont ever see it. A day you buy P55 it is obsolete.[/citation]

It's not $100 difference its $80 for CPU, $100 for equivalent MOBO and $50 more for ram. That's $230. Also, unless you're planning to upgrade in a year's time (in which case what's the point of building a 2 GPU system, unless you're rich), then it makes no performance difference. In less than 2 years Sandy Bridge CPU's using 22nm will be out and the X58 will be as obsolete as P55.

I see no advantage to x58, in fact it's worse performance for more money if you just get a 5970.
 
Bravo. Well if you guys do get a chance to test out the motherboards with newer and "even" specs AND get sponsers to lend or give you 2 5970's and 2 Gtx295's then you can test 4 gpus on crossfire AND SLI.

These tests help alot to prove whether the older X58 is worth getting over the P55 entirely. I am about to order the X58 but am deciding which one to get through your older comparison articles. Thanks and also if you could compare the gpus for other applications like video encoding, cs4, or 3dsMax... it would be great. Thanks
 
[citation][nom]neiroatopelcc[/nom]I've not heard of anyone upgrading a CPU in an existing motherboard since Socket A. So it essentially doesn't matter if you can replace your expensive i7-920 with a better one later and not your cheaper i5 one. Think of the $100 price difference as a 50% price increase over the baseline system - the system which doesn't perform anywhere that much worse AND uses less power but with more turbo (ie. non overclockers get quality too)[/citation]


Youve never heard of people upgrading their CPU on a motherboard? What? Do you know how many readers and PC builders have done just that and you are assuming something like that? Since socket A?!? Pls. rephrase your statement as it doesnt make any sense even for an opinion it is so base...
 
Its some AMD's fans backward logic thats trying to bash the 1156 platform because it so made the AMD product line extinct. And its no more expensive. Sorry but you can run a 5970 in a 102 dollar ud2 1156 Gigabyte board if you please. Or you can choose to run both SLI OR Crossfire with a slightly more expensive board. That spells win.
What counts is how your system runs today. Not what you might do next year after you hit the lottery and decide to buy 3 , 400 gpu's. I think
if that came about you could invest in a new m/b as well.
AMD logic = LOL
Game Set Match
 
What counts is how your system runs today.

------

Yep My Phenom II 940 BE has been beating i7's at HQ for a year now, and I expect it to continue.
 
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