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When will PCI-E 2.0 be bottleneck?

G

grandpatzer

Gawd
Joined
Feb 24, 2010
Messages
641
Would 2x 7990 used in 2x PCI-E 2.0 in x16/x16 start to bottleneck?

After logging and seeing how low my cpu use is with 2x 6950 2gb I think phenom II overclocked should handle 7990 in crossfire.
Currently when gaming my CPU core load is nowhere close to 100% core load.


Edit--> obviously a hypotethical question but assumion 2x 7970 is equal to 7990
 
My guess: when (or, more realistically, if) games start to leverage the compute functions of GPUs. The only time that PCIe 3 showed any benefit has been in compute applications (I think it was video encoding, but I can't find the link to the test right now). So unless some new game uses the GPU to do some bandwidth intensive task during gameplay, I don't think a new video card is going to hit a wall with PCIe 2 speeds any time soon.
 
Good to know That was pretty much my deciding factor on selling my 6950 or not I am just going to buy another 69x0 once the 7970's hit/ when prices drop.
 
grandpatzer said:
Would 2x 7990 used in 2x PCI-E 2.0 in x16/x16 start to bottleneck?

After logging and seeing how low my cpu use is with 2x 6950 2gb I think phenom II overclocked should handle 7990 in crossfire.
Currently when gaming my CPU core load is nowhere close to 100% core load.


Edit--> obviously a hypotethical question but assumion 2x 7970 is equal to 7990
Click to expand...
Just because your CPU isn't at 100% load doesn't mean it's not a bottleneck. I can guarantee if you upgraded to a Sandybridge-based Intel CPU you would see a noticeable improvement in frame rates.

Putting 2x 7990s (estimated cost of $1600) in a PhenomII system is silly. If you upgrade to that much GPU power, upgrade the core of your system as well.
 
rizen pretty much hit it.. i'm an AMD person but i'd laugh my ass off at anyone that put 2 7990's in a phenom II based system.

currently at 3.8Ghz your cpu is not the bottleneck of the system but putting 2 7970's or even a single 7990 it will definitely become the bottle neck.
 
To answer your original question, no, two 7990's would not fill the bus at 16x/16x.
 
It'll be quite some time. Thankfully, with the introduction of PCIe, we have a bus that is growing faster than demand. That's great and how it should be. The bus shouldn't be a bottleneck.

I really doubt it'll end up being an issue for the most part. By the time things are maxing the 2.0 bus, everything will be on something newer.
 
Magnus said:
To answer your original question, no, two 7990's would not fill the bus at 16x/16x.
Click to expand...

With eyefinity resolutions on the 8x/8x motherboards that most of us use today I wouldn't be surprised if it did hold back a couple of 7970s.
 
BababooeyHTJ said:
With eyefinity resolutions on the 8x/8x motherboards that most of us use today I wouldn't be surprised if it did hold back a couple of 7970s.
Click to expand...

16x has a max bandwidth of 8000 MB/s. So, a 7970 is not going to fill it.
 
It already is for some applications. Game developers aren't going to purposely bottleneck PCIe 2.0 until most targeted systems have something faster.

Having a faster bus may help games which rely on virtual texture memory schemes, and also GPGPU applications which use large sets of data at once.
 
BababooeyHTJ said:
and with the popularity of 1155 that effects crossfire users how?
Click to expand...

Not sure what you're saying. Sandy Bridge still uses the 16x bus. A 16-lane PCIe 2.0 bus transfers 160 Gbps unencoded, which is 128 Gbps of encoded data. That’s 16 Gbytes/s of encoded data. So. an 1155 would be even less bottle necked by 7970.
 
Last edited:
Uh no, he is talking about running two 7970's in 8x/8x mode which is already a limiting factor. Here you can see paltry GTX480's being limited:

farcry2_1280_1024.gif


For Ivy Bridge users with Z77 and two 7970's at 8x/8x, PCI-E 3.0 will be a nice upgrade versus PCI-E 2.0
 
Nexus6 said:
Highly unlikely.
Click to expand...

lol ok.

1281921810rimGokAidL_3_5.gif


Just 1 card dropping down (one of the cards still at 16x) to 8x already limits a two generation old GPU yet two 7970's wouldn't be limited on 8x/8x PCI-E 2.0? :rolleyes:

That's fine, you can keep PCI-E 2.0, I'll take 3.0.
 
Vega said:
lol ok.

1281921810rimGokAidL_3_5.gif


Just 1 card dropping down (one of the cards still at 16x) to 8x already limits a two generation old GPU yet two 7970's wouldn't be limited on 8x/8x PCI-E 2.0? :rolleyes:

That's fine, you can keep PCI-E 2.0, I'll take 3.0.
Click to expand...

Why thank you for using my links to prove a point that that I already made, while making yours look worthless.

99% of people will never have a need to spend ridiculous amounts of money $ on worthless features like PCIe lanes. :rolleyes:

If you're part of that 1%, want a cookie? Go have one on my behalf but don't come in threads and spread false information that doesn't apply to most of us.
 
So you're making that conclusion based off of three games? Thats a very limited test. It would be like testing a cpu in those vga limited games and saying that cpu horsepower doesn't help for gaming. There were also some surprising results at the TPU link. Are you just going to throw out those results?

Also you're acting like upgrading to a mobo with pci-e 3.0 is a "ridiculous amount of money" but something like 7970 crossfire or three monitors are cheap. That made me laugh.

Am I going to be in a rush to go out and upgrade my p67 sabertooth? No, but I'm also not going to be running 7970 crossfire or eyefinity. For those people it might not hurt.
 
KayossZero said:
Why thank you for using my links to prove a point that that I already made, while making yours look worthless.

99% of people will never have a need to spend ridiculous amounts of money $ on worthless features like PCIe lanes. :rolleyes:

If you're part of that 1%, want a cookie? Go have one on my behalf but don't come in threads and spread false information that doesn't apply to most of us.
Click to expand...

Oh ya, I must have missed the part about only being allowed to talk about single GPU / 1080P setups! :rolleyes:

Man that is [H]!

I forgot these forums are being overrun with basic computer users. It doesn't apply to you so that makes it false information. Nice logic there.
 
Meanwhile you're missing the entire [H] theory of GPU comparison. Performance differences too small to toggle any image quality features really don't matter.
 
DanNeely said:
Meanwhile you're missing the entire [H] theory of GPU comparison. Performance differences too small to toggle any image quality features really don't matter.
Click to expand...

In those three games with the cards that they used. Thats too small of a sample size to be making any sweeping generalizations especially with next gen cards.
 
Rizen said:
Just because your CPU isn't at 100% load doesn't mean it's not a bottleneck. I can guarantee if you upgraded to a Sandybridge-based Intel CPU you would see a noticeable improvement in frame rates.

Putting 2x 7990s (estimated cost of $1600) in a PhenomII system is silly. If you upgrade to that much GPU power, upgrade the core of your system as well.
Click to expand...

sirmonkey1985 said:
rizen pretty much hit it.. i'm an AMD person but i'd laugh my ass off at anyone that put 2 7990's in a phenom II based system.

currently at 3.8Ghz your cpu is not the bottleneck of the system but putting 2 7970's or even a single 7990 it will definitely become the bottle neck.
Click to expand...

But I don't understand how that is possible, the most modern games my cpu@3.4ghz reaches 2 cores rec 70-80% 3rd core 50% and 4th 30% at most.

Why would min fps increase with Intel when my CPU is not at 100% load.

btw in Dirt3 I can make my 2x 6950 GPU core load 99% on both.
 
KayossZero said:
Why thank you for using my links to prove a point that that I already made, while making yours look worthless.

99% of people will never have a need to spend ridiculous amounts of money $ on worthless features like PCIe lanes. :rolleyes:

If you're part of that 1%, want a cookie? Go have one on my behalf but don't come in threads and spread false information that doesn't apply to most of us.
Click to expand...

When you consider that the OP who asked the question is willing to shell out for dual 7970's, an $1100+ purchase, I think the poster does qualify as an upper tier graphics user. Those links and Vega's use of them are quite valid to demonstrate it is most likely worthwhile for the OP to have x16/x16 PCIe 2.0 at a minimum to get the best bang for buck, such as can be had with that expensive of a purchase, when using two 7970s. At higher resolutions or if a third card is added later, x16/x16 3.0 will be even more useful.

Yes, I would like and do demand that you deliver not less than one fresh, still warm and moist, semi-sweet chocolate chip laden sugar cookie!
 
Unless I'm missing something my CPU is not bottleneck?

Ive read a eyefinity review of 7970 and they compared a stock i7 920 to i5 2500k and 5760x1080
There was virtualy no difference between those and fps.
http://widescreengamingforum.com/article/amd-radeon-hd-7970-review-cpu-comparison-w-core-i7-920

Unless I'm missing something my 965be@3.8ghz or if I upgrade to 960t@~4.0-4.2ghz I should be seeing no bottleneck?

I think I saw some benchmarks in games where the i7 920 is better than 3.8ghz phenom but there even are games where the phenom OC is better then o7 920.
 
Man why does everyone get their panties in a bunch?

Most of the results shown for the discrepancies between the PCIe lanes actually fall within the margin of error, so they're really irrelevant.

PCIe 3.0 will be beneficial sometime in the future, most likely not anytime soon unless you're benching, GPU crunching etc.

Although, why not just get a z68 board and when Ivy-bridge comes out have a direct drop in and PCIe 3.0 right along with it? That's what I did.

As for the i7 920, it's a great CPU, really powerful STILL. I had no issues maxing any game with my old 920 and it definitely didn't bottleneck any video cards I ran in SLI or CF --even at stock speeds.
 
grandpatzer said:
Unless I'm missing something my CPU is not bottleneck?

Ive read a eyefinity review of 7970 and they compared a stock i7 920 to i5 2500k and 5760x1080
There was virtualy no difference between those and fps.
http://widescreengamingforum.com/article/amd-radeon-hd-7970-review-cpu-comparison-w-core-i7-920

Unless I'm missing something my 965be@3.8ghz or if I upgrade to 960t@~4.0-4.2ghz I should be seeing no bottleneck?

I think I saw some benchmarks in games where the i7 920 is better than 3.8ghz phenom but there even are games where the phenom OC is better then o7 920.
Click to expand...

You can't take timedemos from a couple of games and make generalizations like that. I saw and improvement in performance when moving from i7 860 to an i5 2500k in quite a few games. There is no way that phenom 2 isn't holding you back in Skyrim for example.
 
BababooeyHTJ said:
You can't take timedemos from a couple of games and make generalizations like that. I saw and improvement in performance when moving from i7 860 to an i5 2500k in quite a few games. There is no way that phenom 2 isn't holding you back in Skyrim for example.
Click to expand...

Unless timedemos use less CPU compared to realgaming I think the phenom II is valid.

Obviously games like BF3, COD and Skyrim are more CPU intensive games than the ones in the link I posted, still the phenom II should be getting me atleast 60fps with eyefinity resolution and xfire 7970, no?
 
Magnus said:
16x has a max bandwidth of 8000 MB/s. So, a 7970 is not going to fill it.
Click to expand...
@ 16x
PCI-E 1.0 - 2,000MB/s up/down (4,000MB/s total)
PCI-E 2.0 - 4,000MB/s up/down (8,000MB/s total)
PCI-E 3.0 - 8,000MB/s up/down (16,000MB/s total)

Yeah, it's going to take a lot to fill more than 2.0 can provide.
 
Red Falcon said:
@ 16x
PCI-E 1.0 - 2,000MB/s up/down (4,000MB/s total)
PCI-E 2.0 - 4,000MB/s up/down (8,000MB/s total)
PCI-E 3.0 - 8,000MB/s up/down (16,000MB/s total)

Yeah, it's going to take a lot to fill more than 2.0 can provide.
Click to expand...

Ive heard the 7970 uses 8000MB/s, so then OC it's possible 2.0 is not enough?

OC 7970 would then be ~10000MB/s
 
and if you plan on running in crossfire on 1155 or 1156 you're running at x8.

grandpatzer said:
Unless timedemos use less CPU compared to realgaming I think the phenom II is valid.

Obviously games like BF3, COD and Skyrim are more CPU intensive games than the ones in the link I posted, still the phenom II should be getting me atleast 60fps with eyefinity resolution and xfire 7970, no?
Click to expand...

No, I would be surprised if a phenom 2 didn't hold you back significantly with such a large fov in known cpu limited titles. Lets face it if you you can afford $1100 worth of graphics cards and three monitors you can afford a decent cpu.
 
Doh of course that timedemos use less cpu than the actual game!

Timedemos on a rail nature and repeatability comes from having anything ressembling an AI turned OFF, and thus it is a much lower load on the cpu than the actual game.
This is common knowledge people! >.<
 
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