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Radeon HD 5770 and the Concept of Bottlenecking

Last response: in Graphics & Displays
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March 28, 2011 3:08:05 AM

Hi there.

First, off, my apologies if what I am asking is considered to be basic knowledge in terms of upgrading video cards, but I have tried researching on my own about this issue for a fair amount of time and I am still finding that I come up at dead ends with no real concrete answer. I'm also sorry if this belongs in another section of the forum; I did believe that it would be more suitable to post here seeming it pertains to me deciding whether or not to buy certain video cards.

Anyway, I have been reluctant to buy the XFX Radeon HD 5770 (or any other previous-gen card for that matter), because I keep hearing mixed opinions about the importance of having a collectively decent CPU and video card. From my understanding or what I've researched, in basic laymans terms, the concept of bottlenecking is that, if we're talking in my potential scenario, the video card would have already processed the information and would then wait for the CPU to catch up, thus limiting the performance of the card, and this would be vice versa for a video card that is inferior to the CPU.
What I want to know however, is if this is such a significant deal? Depending on what source I got my information, I've been told things varying in opinion from it not making too much of a significant effect(or course depending on the card and CPU in question) and/or would only lose a certain amount of performance to a certain percentage, to opinions that it may possibly end up performing worse than the card I originally have. I do plan on upgrading my CPU and Mobo at some point next year to something like the Intel i5 or the Phenom II X4, but due to lacking the budget to buy both at the moment, I've decided to stick with a video card for the moment.


So, basically, what I'm asking is thus:

1) Could someone explain the concept of bottleneck in terms of any hardware, including internal bottlenecking within the hardware device itself, and

2) If I choose to upgrade my video card to a Radeon HD 5770, will the GPU bottleneck my current CPU (as well as other aspects of the system, if applicable) and if so, to what degree?

Here are my Specs:

Gigabyte K8NXP-SLI Mobo
AMD Athlon 64 3500+ Processor OC'd to 2.4Ghz
2GB DDR2 RAM
180GB SATA Hard Drive + 1TB External Hard Drive
Nvidia GForce 6600GT GPU
620 Watt PSU
Running Windows XP Professional

Thanks.
March 28, 2011 3:42:53 AM

Quote:
If you buy a fast gpu and run it at a low resolution the cpu will bottleneck coz its not fast enough to keep up with the gpu.
Also a old slow cpu is not fast enough to keep up with the gpu.

If you buy a card do the following

Monitors native resolution->gpu->cpu that can keep up with it


When you say "low resolution", what kind of resolutions are you talking about? I was planning to run at either my monitor's native resolution (which is 1920x1080) or at a resolution slightly below that like 1600x900 or even 1280x1024 if necessary. If it does bottleneck, what would that entail? Does it mean games would be made unplayable or go at very low framerates?
March 28, 2011 3:54:12 AM

Hi there,

I personally think that the cpu will bottle neck the gpu, as it will preform alot better than your cpu, thus holding your performance back.

If i were you i would run a better cpu (an AMD, obviously :)  ), and you will get way better performance.

Cheers,

xXCozter8Xx
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March 28, 2011 8:24:12 AM

Quote:
depends on the gpu. At lower resolutions the cpu plays more a role coz the gpu will have less work to do and will run through its work quicker. 1280x1024 they benchmark cpus on normally coz that's where it plays a big part. at 1080p it don't play so much of a part.
Remember you will only get 60fps or 120fps max out of a card on a LCD. A gpu and a LCD need to sync to avoid tearing issues. So at any resolution you'll see only 60fps or a 120fps depends on your LCD.
When you use a dual gpu setup coz some part of it is being done via software a quad cpu minimum is required. Anything less and you will run into bottleneck problems.

Normally with a single gpu a dual core cpu running above 3Ghz is fine and should not bottleneck it as it is able to keep up with the gpu



So higher resolutions are less likely to bottleneck the CPU? What I'm still trying to understand is the effects and consequences of bottleneck itself, instead of the question of whether it'll bottleneck or not. I think it's fine to assume that my CPU will bottleneck this card, but what does this mean? Like I said, I've heard mixed views about the effects of bottlenecking and im confused as to whether this'll severely or slightly affect the performance capabilities of the card or not
a b U Graphics card
March 28, 2011 9:07:45 AM

Bottlenecking only means (here) that if you had a faster CPU you may be able to squeeze out more frames. It won't cause you to stutter any more than say a slower GPU that more matched your CPU. At the lower resolutions your FPS won't go as much higher as it should.

A higher resolution stresses the GPU, producing less frames. Thus less instructions your CPU has to deal with. Your FPS will never go up when you raise your resolution, or become any more playable (in case that wasn't assumed).

Some of the more GPU bound games you may do ok. However, some games will demand a little more from the CPU and you'll definitely see some performance hits.
a b U Graphics card
March 28, 2011 12:36:52 PM

Wow well, to be honest you're using way way old hardware there. There are dual core socket 939 cpus out on the market, however you would need to make sure your particular board would support said cpu's before picking one up. Regardless, a HD 5770 would be held back badly by any socket 939 cpu you could buy other then a FX-60, which would still present some bottleneck issues. Personally, I would take the money you plan to use on a 5770 and buy a AM2+/AM3 board that uses DDR2 so you can keep your current ram, and pick up a Athlon II X3 or X4 cpu. After it arrives and you get it up and running stable, sell off the old parts, and put that money towards either a HD 5770, or maybe even one of the older but still decent Dirext X 10-10.1 cards like a HD 4830 or a Geforce 9800 GTX that fall in the $40-60 range. Doing that would get you a huge performance gain over your current set up, and at a very reasonable price range.
a c 147 U Graphics card
March 28, 2011 1:58:51 PM

Your RAM, CPU and probably your hard-drive are all way under what the 5770 is capable of.

As the above post said, you can upgrade the CPU and probably the RAM to 4 gig and it will match the 5770 a bit better.

Or you can just get the 5770 and move it to a new system. Which may be better use of money than upgrading your current system.

You will see a good bump in speeds over the 6600 with just the video card, but not nearly as much as you would if you got the 5770 along with a whole new platform.
March 30, 2011 1:10:27 PM

professorprofessorson said:
Wow well, to be honest you're using way way old hardware there. There are dual core socket 939 cpus out on the market, however you would need to make sure your particular board would support said cpu's before picking one up. Regardless, a HD 5770 would be held back badly by any socket 939 cpu you could buy other then a FX-60, which would still present some bottleneck issues. Personally, I would take the money you plan to use on a 5770 and buy a AM2+/AM3 board that uses DDR2 so you can keep your current ram, and pick up a Athlon II X3 or X4 cpu. After it arrives and you get it up and running stable, sell off the old parts, and put that money towards either a HD 5770, or maybe even one of the older but still decent Dirext X 10-10.1 cards like a HD 4830 or a Geforce 9800 GTX that fall in the $40-60 range. Doing that would get you a huge performance gain over your current set up, and at a very reasonable price range.


Would the Phenom II X2/4 be a more ideal choice? i hear they are slightly more efficient over the Athlon II processors (at stock speeds) however they seem to be slightly more steep in price.
a c 147 U Graphics card
March 30, 2011 1:45:49 PM

I'd not spend money on an obsolete chipset with CPU upgrade. Get the video card now, and get together $200 or so for a full refresh. A fast single core will handle games OK, maybe not at the highest setting that the video card is capable of, but good enough to run smooth.

A cheap AM3 motherboard is about $60-70, RAM another $50, CPU, bit over $100. You already have a workable power supply and probably the case is OK. You may want a new drive, a new Samsung F3 or a WD Black will be a good boost from your old drive.

Spending money on a CPU for your socket, is not the best use of money IMHO.
a b U Graphics card
March 30, 2011 1:49:05 PM

The RAM is fine, there is almost no difference between ddr2 and ddr3.
a c 147 U Graphics card
March 30, 2011 1:58:52 PM

eyefinity said:
The RAM is fine, there is almost no difference between ddr2 and ddr3.


Speed yes, amount is a bit low to pair with a card like a 5770. To do justice to a 5770 you really want a quick dual core or a quad, and 3-4 gig of RAM.
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