Sign in with
Sign up | Sign in
Your question
Closed

Will Two 6870s Be Bottlenecked by a Core i7

Last response: in Graphics & Displays
Share
Anonymous
October 7, 2010 3:13:00 PM

Before you read, please understand that this is more of like a suggestion for a future Tomshardware article, rather than a real question, since everything would be speculation at this point in time. Tomshardware readers, feel free to take a stab at predicting the future if you’re feeling lucky.

Will 6870s in CrossfireX Be Bottlenecked by a Core i7?

This question is ambiguous as it stands; let me clarify a few things.

When I refer to "i7", I am talking about one which is based on the LGA 1366 socket/chipset, and costs equal to or less than about $300 (“about” refers to shipping and other small costs). This includes the i7 950, 930 and maybe the 920 if you bought one/got one before they stopped selling it (basically, processors within the budget area of an upper mid-range/high range gaming computer).

I am not speaking about a stock clocked model; I'm referring to one which is clocked in the range of 3.9 - 4.1 GHz, as those numbers seem to be well within reach of the listed processors.

Other assumptions to be made: this hypothetical testing rig would contain 6GB of RAM (of course), be based off a sufficiently fast SSD (for really consistent results, this is more of a “just in case” factor, I am not insulting HDDs), have a capable motherboard (PCI E X16 2.0 signaling for both 6870s, of course), and basically not limit the CPU/GPUs in any out of the ordinary way.

I suspect that most sites are going to use a 980X to test these cards, and I completely agree with that choice within the context of trying not to limit the graphics subsystem (It would be strange if they did not use that processor).

I would suggest that they (tech sites) compare an overclocked i7 950/930/920 (at about 4 GHz) to the 980X at the same clock so that a reasonable comparison can be made. I am aware that the 980X has two more cores, but as most know, the chance of more than four cores making a difference is extremely small in most games. The point of this is to compare architectures and see if entry level Nehalem (LGA 1366) is too slow for two 6870s.

I know I left quite a few things out that could have been further clarified, but please, just use common sense and know that I am not assuming something illogical with regard to my own objectives (hopefully).

A note to tech site writers/testers (assuming they are aware of this post at all), I understand getting two 6870s would be near impossible for a preview. I also realize that even if you get them, there are crazy time constraints. So I only can tell you that I wish you get two cards and have enough time to get all the information I’m asking for before the 6870 is released (I want to avoid subsequent price increases).
October 7, 2010 3:41:34 PM

No two midrange cards in crossfire wont bottleneck an i7

Mactronix :) 
Score
0
Anonymous
October 7, 2010 4:41:45 PM

-Mactronix

You make a good point by questioning the pure power that the 6870 will bring to the table, but I would not consider the 6870 to be a mid-range part.

I use the term "6870" loosely to refer to the most powerful single GPU card ATI (now technically referred to as AMD) will come out with using their next architecture (maybe I should have specified that). I believe you are referring to the Barts XT GPU that Tomshardware had a news article on a few days back. I would expect them to label that the 6770, but even that mid-range card looks like it is only going to be behind the 5870 (performance wise) by about 10% plus or minus 5% (according to the chart that was posted with the news article was the real deal).

This leads me to think that the 6870 is going to be approaching the power of a 5970 if they do like they did with the 5000 series and double from X7XX to X8XX (in this case, Barts XT to Cayman XT).

I've tried finding reviews of dual 5970s in order to see how CPU power played a role, but that would only give an extremely rough (if not irrelevant) idea of what two 6870s will need in terms of CPU power. Plus there weren't enough reviews (that I could find) that were differentiated only by clock rate of two appropriate i7s, so they couldn't be fairly compared.
Score
0
Related resources
October 7, 2010 4:51:32 PM

Naming schemes aside, although we did just get some CCC screen shots of the 6870 being the barts card, which logic says should be 6770 but it seems isnt.
Anyway taking your premis of assuming the top single GPU card then i have another question for you and quite an important one as its a detail you have left out that will make the answer to the question totally differant depending on your answer.
Whats the theoretical monitor configuration here ?

Mactronix
Score
0
Anonymous
October 7, 2010 5:19:01 PM

-Mactronix

Resolutions/monitor configuration were addressed in my first statement regarding that this is really a suggestion for a review. So the resolutions that are normally included (up to 2560 X 1600). Eyefinity results would be nice, but that's really wishful thinking. I don't plan on going the Eyefinity route anyways, so it isn't that much of a factor to me.
Score
0
October 7, 2010 5:36:00 PM

So is your real question then this:
During a review of the two highest performing single ATI GPU's from the 6 series would an i7 (as specified by yourself earlier) experience any bottle necking.

The answer then is a definite yes as these reviews start at resolutions where such hardware would definitely be restricted, that being what most people refer to as a "bottleneck"

Mactronix :) 
Score
0
Anonymous
October 7, 2010 6:15:41 PM

-Mactronix

Yes, you can definitely assume that the CPU is going to be a bottleneck at low resolutions, but you don't get two 6870s to play at anything below 1920 X 1080 (I mention that resolution specifically, since monitors get really expensive above that, so much so that it would go out of what I would consider an "upper mid-range/high range gaming computer").

My personal question (in long form) is; when comparing an entry level Nehalem (LGA 1366) to a faster architecture (let's say Westmere), will there be a noticeable difference in performance at a meaningful resolution in a graphically intensive game (by current standards), so that it would not be logical to build/upgrade to the lower of the two configurations (with Nehalem) due to a CPU/GPU subsystem balance issue.

I really don't like constricting my statement because the more information this theoretical review would have the better. The question above is my purpose for wanting these results, in any case, more data is always nice to have.
Score
0
October 7, 2010 7:19:50 PM

Ok well thats going to be subjective now then isnt it. I'm not trying to be funny or obstructive here but it does all come down to personal preference as far as settings etc are concerned when deciding if X hardware will as you said make a noticeable difference in performance at a meaningful resolution in a graphically intensive game.
I would think that, having looked at some reviews of cross-fired 5970's and finding that some games do in fact prove to be CPU limited, that the chances are that some games will continue to be so restricted using 2 X the best single 6 series GPU.
Having said that its not a bringing the PC to its knees type restriction we are seeing in these situations, its usually older games with the FPS being north of 80+.
Most games show in the reviews that there is still plenty of room left in newer games for more GPU power without showing any signs of running into a CPU restriction anytime soon.

Its almost certain that the newer faster CPU's that come along will bring more FPS to a system regardless of if there is already an evident restriction or not, overclocking a CPU will give the same results but that doesn't mean there is a restriction there worth worrying about. The question is do you really need more FPS and to me personally i don't really think you do.

Mactronix :) 

Score
0
October 7, 2010 7:35:26 PM

Thomas Soderstrom made a comment about bottlenecking at 1920x1080 or lower with gtx 480's in SLI. He basically said all cpu's bottleneck them to a degree. i7 920@4.00ghz is a good starting point but in some games it still shows. (verbatim) how I understood the comment. Don't have link.
I think its the older cpu's that are less of a good match for the newer more powerful gpu's. To make a complete judgment on AMD cpu's we need sites to run 955,965's at 4.00ghz and run the new amd cards in crossfire on their native chipset motherboards.
And analyze the results, I hope we see that.
Score
0
October 7, 2010 7:50:52 PM

If the new article here on Tom's tells us anything, it's that almost no games use a ton of CPU power once you get to quad cores... except GTA 4. So, overall my feeling is that you may see some FPS increases with a little more CPU juice, but that could easily be from other factors like faster memory or faster QPI.

Obviously you can bottleneck the cards simply by reducing the resolution and game settings, but if we're trying to play at least 1080p with everything at max detail, I'm confident 60fps would be acheivable regardless of the potential CPU bottleneck.

So basically as the last two comments are stating, at this point the "bottleneck" wouldn't be anything worth considering as the FPS will be either GPU bound in most extremely intense games/setups (eyefinity) or the FPS will be so high it won't matter anyway.
Score
0
Anonymous
October 7, 2010 9:27:01 PM

This question is hopelessly relative to many factors, I get that. I know changing the CPU is going to make a difference, I'm just asking how much of a difference will that be.

It's better to look at this question in terms of a suggestion for a future article, because what the consensus seems to be is that no one really knows with enough certainty what is going to happen. Sure, we know performance is going to increase, but this question is so subjective that it needs to be thoroughly analyzed, the kind of way that produces a lot of data. Hence, why I prefaced the thread.

What I am looking for is more of a trend that's gathered, rather than a straight answer. I want to see how FPS react in different games at different resolutions.

Score
0
October 7, 2010 9:54:47 PM

Quote:
This question is hopelessly relative to many factors, I get that. I know changing the CPU is going to make a difference, I'm just asking how much of a difference will that be.

It's better to look at this question in terms of a suggestion for a future article, because what the consensus seems to be is that no one really knows with enough certainty what is going to happen. Sure, we know performance is going to increase, but this question is so subjective that it needs to be thoroughly analyzed, the kind of way that produces a lot of data. Hence, why I prefaced the thread.

What I am looking for is more of a trend that's gathered, rather than a straight answer. I want to see how FPS react in different games at different resolutions.


Based on rumor and speculation. 1 6870 (high end)=135% 5870. So 120% GTX 480. We have no idea on scaling. Therefore, id assume 2 6870s would be 130-150% 2 480s. It depends on the game and the resolution, but id imagine it would start to reach its limits. Not that it really matters though. 2 6870s should be so powerful, even 2 480s, that any game that gets to the point of being CPU limited will be so high in FPS it wont matter.
Score
0
Anonymous
October 7, 2010 10:48:49 PM

-Ares1214

Agreed, I like those numbers you estimated, they seem very realistic (on the safe side).

As a disclaimer, my question is a bit weird in that I am looking at things in a highly technical way, rather than practically. It is not a question of whether it's playable to me, it's a question of percentages and relative losses of efficiency. Don't get me wrong, I usually don't look at things this way (probably why I got the outcry that I did).

This is just like anything else, as soon as you think of something in a different way, it changes everything.

Nice responses, keep it up.
Score
0
October 7, 2010 11:40:01 PM

Id actually assume at launch, scaling might not be terribly good, but after 1, or a few driver updates, it may get a lot higher. It depends how they want to do things. Although they did say scaling was one of the things they were aiming to improve.
Score
0
October 8, 2010 12:21:37 AM

Starcraft 2 is bottlenecked by a Core i7 at pretty much every detail level (see Toms Starcraft 2 revisited article), so yeah if you have software that doesn't utilize all 4 cores then even the best Core i7 will bottleneck it (and probably on some software that does utilize all 4 cores). So I think the theoretical answer to your theoretical question is that there is no processor available today that will never create a bottleneck for dual theoretical 6870s. For most modern games at normal resolutions (1980p and below) your bottleneck with that kind of rig would probably be the refresh rate of your monitor so it wouldn't make a crap's bit of difference anyways.
Score
0
October 8, 2010 8:36:06 PM

Quote:
According to semiaccurate.com, a few leaks do support that the name "Barts XT" will be used to denote the 6870. I revise my statement of naming schemes.

http://www.semiaccurate.com/2010/10/08/amd-barts-turns-...


Yeah, this rumor has been floating around a while, and it appears to be more and more true, but not definite yet. We shall see.
Score
0
Anonymous
October 16, 2010 3:59:57 AM

Yeah, 6870 is definitely going to be Barts.

http://www.semiaccurate.com/2010/10/15/radeon-hd-6800-s...

(additional information on the cards which will be released next week)

So, what should I have called the most powerful card that AMD is coming out with? I guess Cayman XT would have been the safest bet, because of how different the number system is going to be this time around.

Information on Barts is all over the place now; has anyone found anything on Cayman XT other than pure rumors, something more along the line of specs/numbers?
Score
0
October 16, 2010 4:13:02 AM

Quote:
Yeah, 6870 is definitely going to be Barts.

http://www.semiaccurate.com/2010/10/15/radeon-hd-6800-s...

(additional information on the cards which will be released next week)

So, what should I have called the most powerful card that AMD is coming out with? I guess Cayman XT would have been the safest bet, because of how different the number system is going to be this time around.

Information on Barts is all over the place now; has anyone found anything on Cayman XT other than pure rumors, something more along the line of specs/numbers?


850 MHz core, 1600 MHz memory, 1920 shaders, 96 TMU, 1x6 pin 1x8 pin, power consumption above 5870 below 480, new cooler design...thats about all we know.
Score
0
October 16, 2010 6:35:33 AM

Cards today are bottlenecking the i7 OC'ed to 4ghz with the right game. Bottlenecks occur on every system, when playing the right game.

At the right resolutions and right game, the new cards in CF would bottleneck the i7 too.

Now if you consider 60 FPS to be maxed out performance, then you'll probably find the i7 will almost never been the bottleneck with current games at any resolution and the 6870's will be the bottleneck on extremely high resolutions only, and maybe a few odd games that are extremely demanding.
Score
0
October 24, 2010 1:27:39 AM

This topic has been closed by Mousemonkey
Score
0
!