View Full Version : Bottleneck.
09-23-2009, 06:51 PM
Would a 5870 bottleneck my E8500 stock?
09-23-2009, 06:56 PM
Do you even understand what you just asked?
In order for there to be a "GPU bottleneck", the CPU would have to be a limiting factor. Do you know of any games in which an E8500 outputs a low fps? Neither do I.
On the other hand, any random game maxed out at 1920x can give the 5870 a run for its money.
09-23-2009, 07:03 PM
lol sorry i meant to ask that the other way around
09-23-2009, 07:04 PM
depends on the resolution and game
some games, or even just spots in games might be more performance limited by any CPU, other games/spots will be limited by any video card
..however, the same things(visual effects and resolution) that would be limited by the video card, are not the same things(what actually happens, not what they look like) that would be limited by the CPU...so really there is no such thing as a "CPU>video card" or "video card>CPU" bottleneck for any/every situation...only "CPU≠video card" as they just don't do the same jobs at all...and you could always change the settings or game to shift which is more in demand as the limitation in performance
09-23-2009, 07:30 PM
SRY to hijack the thread but i have a similar question. Would a 5870 pair well with a Athlon x2 7750+ Kuma 3.2GHZ? Keep in mind this is only temporary until i can afford a mobo ram and cpu combo.
09-24-2009, 06:40 AM
I think the main thing to consider is that any video card will not make any CPU perform any worse
so you could check what your CPU is capable of(with any video card, before you got a better one) by using settings in a given game that will show just how well the CPU can operate...so you would lower all the visual settings: like set to the lowest resolution, no AA/AF, lower in-game and driver image quality and effects levels, drop the DirectX level down to Dx8 or Dx9, etc. basically everything you could do to make the game look like crap so the 'job' the video card has to do(even an older lower performing card) is as easy as possible...and then you should be able to see the highest frame rate that the CPU can produce, as it does the calculations on what things are "in" and is "happening" in the game(not what they look like)...basically the video card will have as little as possible to do with the performance of the game
...once you see what the CPU is capable of, with just the things the CPU has to do(different from the job the video card does) running, without any load placed on the video card...then you can try to maintain that performance level with a better video card doing its job on top of that to 'draw' what everything looks like in the game with all the effects on, higher resolution and AA/AF levels, and full visual quality and DirectX levels
so, you might find that something like an Athlon X2 Kuma @ 3.2GHz will run a game in a range of 20fps ~ 120fps(when the system is set not to draw any demanding graphics with the video card)....but then you would add a better video card and use highest graphic settings(so the game looks great) that is rated to be able to run that same game(at those settings/resolution) in a range of 40fps ~ 100fps
...and what would happen when you paired the CPU(capable of 20fps ~ 120fps) with the new video card to run highest visual settings(at 40fps ~ 100fps)...is that at some spots in the game where there is more demand on what the CPU has to do, the frame rate would drop to 20fps(the video card can never draw any more frames than the CPU gives it)...in other spots(even tho the CPU is producing high fps) there might be the most graphics load and the video card becomes the limitation dropping down to 40fps...ultimately to see the highest fps reported you would need spots in the game where there was the lowest load on both the CPU and video card simultaneously, but then the biggest and final limitation would aways 'cap' those max frame rates that could be displayed, and that is the refresh rate of the monitor, if it can only run at 60Hz, its not going to be able to display more than 60fps anyway
a "bottleneck" I think of as like a river flowing, basically the 'job' is always the same, just moving water, but maybe in parts of that river there is something that blocks, restricts, or narrows the flow, and thus 'holds up' how much water passes thru the whole river because of that one point RIVER
water ---------------------> water flow
bottleneck but I don't think that is what happens with :
CPU -----> video card -----> monitor
..at all, because the 'job' doesn't stay the same from one place to the next, and at some times, one thing might have a harder work load than something else(and it would be the limitation) and at other times something else would be in more demand to perform its job and the limitation would change...and this could happen all within the same game at the same settings, or you could change what the biggest limitation is(the CPU, video card, or monitor) by changing the settings...so you could get: COMPUTER
40fps 40fps 40fps
CPU---------> GPU----------> monitor ---------> you
VIDEO CARD "limitation"
100fps 40fps 40fps
CPU---------> GPU----------> monitor ---------> you
100fps 100fps 60fps
CPU---------> GPU----------> monitor ---------> you ...all with the same settings, with the same hardware, and within the same game depending on what was happening in spots(where the CPU might have more to do) or what things looked like(what the video card has to do) or finally what the monitor is capable of displaying(its resolution and refresh rate)...never ever just always one thing(like the bottleneck in the river) with always the same job being done by everything
09-24-2009, 08:08 AM
If a 5870 can be bottle necked by an OC'd high end i7 then im sure that would be a bottle neck also if not more so.
from what ive seen of the current 5870 reviews from guru3d they pretty much out perform all current cards except the Dual GPU cards maybe such as the 295. so with that said theres going to be alot of bottle necks goin around when people are able to get them. a Bottle Neck is when the GPU transfers data at a rate that the CPU cant keep up with thus creating a bottle neck..
so because of the fact the i7 they used was OC'd and STILL couldnt keep up with the GPU, suffice to say as i said before, theres going to be alot of bottle necks in one form or another especially when better drivers are released.
09-24-2009, 08:25 AM
There's always a bottleneck, no matter what.
At low resolutions, it's mostly a CPU bottleneck and at high ones, it's a GPU bottleneck.
09-24-2009, 10:53 AM
I think T Rush posted a very good explanation. I'll add my two cents.
I personally never really care about whether there is going to be a bottleneck regarding performance. I view my budget as the bottleneck and the rest of the components just flow to the system I want to build to do the things I want it to do. I normally reuse components with the various systems we have in our home and if one system has a component in it that gets to the point where it isn't delivering the performance it should be based on what my expectations are, I purchase a new component and move it to the next lower system in the house, move that replaced component to the next system in the house, etc.
09-24-2009, 11:14 AM
I'm going to make it very simple, Your CPU is good and as is your GPU.
You won't be caused any problems. You can never eliminate bottlenecking anyway, it's always been a non issue for me.
09-24-2009, 02:08 PM
seems like most people believe that this progression of performance starts at the CPU, and if it isn't producing enough work for the video card to do its job on, then the video card is under utilized, or 'held back' by the CPU
...and this is true, as the video card can never draw what everything looks like in each frame, at a faster rate than the CPU does the calculations for what is in or happening in the game...so I guess you could say that the CPU(any CPU) is always the determining factor for maximum "possible" frame rategame = CPU > video card > monitor = you
however, I think its more important and practical to look at each of the 'steps' of limitation from the other direction:
what is the highest frame rate it can display, and what resolution does it run...as ultimately this is actually the game's final limitation("bottleneck") to display the frames to you
this is the next step beneath the monitor, and what video card will it take to run a given game at the resolution and refresh rate of the monitor above it...will it be able to reach the performance level of that monitor? at the visual quality settings with the graphics that are demanded in that game
will this CPU provide data on what is taking place in the game at a rate that is quick enough for the video card above it so that the video card can match the performance level of the monitor ?
..so ultimately, does it matter if the video card can "render" frames at 100fps if the monitor can only "display" 60fps, and then if the video card is only getting 60fps of the 100fps it could draw displayed, does it matter if the CPU can "produce" 150fps?...not really....
so while it might seem necessary to have a better CPU(">" greater than) than the video card, so that the CPU always has data ready for it to be rendered into frames, and that the video card is ">" greater than the monitor and can send it more frames than the monitor can display, you really don't 'see' the benefit from that...of course that has to still happen tho, but its just not necessary to be overly excessive about it, and you need the best monitor to display the performance of a great video card made possible by a good CPU ... and the other way around(the "CPU>video card>monitor") and each step is entirely limited("bottlenecked") by the next...in fact, actually the only way not to be "bottlenecked" is to have a crappy CPU, where next a mild video card could draw every frame it produces, and then a super monitor capable of never being supplied with enough frames from that mild video card to ever reach its max refresh rate
...so thats why I find it so silly when people try to describe any sort of CPU≠video card "limitation" using the term "bottleneck"
I think a lot of people see this all happening like this poster: If a 5870 can be bottle necked by an OC'd high end i7 .... yes, but also a stock speed 2.4GHz old Pentium 4 can be bottle necked by a 5870 if the resolution is 2560 x 1600 with 8X AA 16X AF, maximum quality effects, in a spot of the game where the scene looks beautiful but not much action is taking place...there the 'job' the super high-end video card is required to do is much harder(and will be a greater limit to performance) than the relatively easy CPU 'job'(which is completely different than what the video card is responsible for) that just about any CPU could do
from what ive seen of the current 5870 reviews from guru3d they pretty much out perform all current cards except the Dual GPU cards maybe such as the 295. so with that said theres going to be alot of bottle necks goin around when people are able to get them
so because of the fact the i7 they used was OC'd and STILL couldnt keep up with the GPU, suffice to say as i said before, theres going to be alot of bottle necks in one form or another especially when better drivers are released
take a look at those reviews again, and notice that they test at different resolutions...do you see any of those tests where all the video cards perform the same at all the different resolutions?...as that would be a sign that the max 'possible' frame rate is reached where the CPU is the bottleneck...even at the lower resolutions with the tests they use for video cards, there is still always room for improvement(or should be if they are going to be valid video card tests) and that the CPU is providing way more fps than the video cards can render
also note that in all those tests with different video cards and different resolutions, they are using the exact same CPU that is performing exactly the same, and doing it at a level of performance that any/all of the video cards can not keep up with
a Bottle Neck is when the GPU transfers data at a rate that the CPU cant keep up with thus creating a bottle neck... the problem is that the CPU just isn't "transferring data" to the video card, and then the video card passing that same data on to the monitor to be displayed...along the way things are happening to that 'data', the CPU does one type of processing of that data, and then the video card renders that data into a image of what it should look like...these are two completely different jobs...and at times the CPU's job might be way easier than the video card's(so a weak CPU might be "bottlenecked" by the most powerful video card) and at other times the CPU might just we swamped with a bunch of things that it has to do to complete its job, and the video card just waits for frames to draw(so a weak old video card might be "bottlenecked" by the best highest overclocked CPU)
...the bottom line is that the same types of things in games don't "bottleneck" both the CPU and video card in the same way at the same time, as the CPU and video card do totally different things, unlike the 'river bottleneck' which no matter what just has the sole job of always trying to flow water
09-25-2009, 04:01 AM
T-rush, perhaps it is because I agree with what you are posting, but that is some of the finest posts about "bottlenecking" that I have read, well done.
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