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How do you know if CPU limiting your GPU?

Last response: in Graphics & Displays
April 19, 2004 9:31:45 PM

I would like to get one of the new graphics card coming out (6800), but I only have a 2.0 Ghz processor (400 FSB). Would that be a waste, or will I still see significant improvement over my existing Geforce4 ti 4400? Is there a benchmark or something I can run to test if my processor is limiting my graphics card?

More about : cpu limiting gpu

April 20, 2004 3:39:50 AM

I disagree with Scot. The bottlenecck is preportional. Even with your current cpu you will most deffinitly see a big boost in performance by replacing your card with a 6800 Ultra.

To illustrate what I mean by preportional lets say you get 30fps in some paticular program with your current rig and after replacing your vid card with the 6800 Ultra you may get a boost to say 50fps (completly made up numbers btw). Where as on a system with a much higher speed cpu they may get, lets say 45fps using the same program and with the same video card as you but then get 65fps after replacing the video card with the 6800 Ultra.

The only time you'll notice the cpu being the true bottle-neck is when your playing a game on your system where your close to or already capping out at the max fps that that program is going to allow, in which case upgrading to a better videocard isn't going to increase it much if anything at all. However that works bothways meaning that upgrading your cpu in the same scenario may not result in much of a boost at all depending on exactly what it is that was holding that paticular program from going higher before hand. I say that because every program relies to vaying degrees on the cpu and videocard. So where one program is limited by the cpu another program maybe limited by the videocard.

My point? Upgrading your cpu will give you a performance boost over all but that dosn't mean your current rig is being held back by the cpu anymore then any other piece of hardware in your machine or in everyone elses machine.

<font color=blue>_______________________________</font color=blue>
Asus A7N8X-X, Athelon XP 2500+ Barton,
Samsung 1gb DDR400, MSI GeforceFX5900 XT.
Aquamark=<b>36077</b> 3DMark03=<b>5322</b>
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April 20, 2004 4:01:52 AM

I have to side with Vimp. He is right overall and specifically because some programs are, indeed, more dependent on the CPU while others are more dependent in the GPU.

Scottchen is also right however. Putting a sate of the art video card into a lower mid-range machine is a waste in the sense that it is like installing heated leather seats in a 1988 Chevy with 200K miles on it.

Strive for a harmonious system where all components are the same generation. If you manage to build such a system it will bring you a lot of joy over a very long time (at the very least 2 years).

You will get better performance from your PC with the nV6800 but it will not be as noticeable and the actual boost may not feel like it was worth all the money spent.

Finally, if you do upgrade your CPU and motherboard, say a year from now the video card most likely will become obsolete and the cycle will repeat only now you will have a kick-ass CPU and a sub-par VGA card. Try to avoid this because this way your performance will always be lacking.

The hottest CPU of today, the Pentium 4 Extreme Edition, is barely adequate for the 6800 but they work together well. Go for it, tiger.

<font color=green>Stingy people end up paying double. One kick-ass rig that will go strong for three years or one half-decent one every year?</font color=green> :cool:
April 20, 2004 4:26:43 AM

You pretty much won't see the full potential of the card on that system. Considering upgrading to P4 Prescott or Athlon64, if cash's available. If not just buy a new heatsink, and overclock the crap out of your processor, your processor should hit 2.5-2.6ghz no problem.

<A HREF="" target="_new">My PC</A>
April 20, 2004 5:09:25 AM

Again I strongly disagree. Infact I'd go as far as to say that his current rig would quite likly notice a bigger percentage increase in performance in 3Dgames if he got the 6800 Ultra then would someone with basicly his system but a much higher cpu speed who also upgraded to a 6800 Ultra. You need to remember that games are much more dependent on the videocard then any one of the other components. I would no more call it a waste for him to buy the 6800 Ultra then I would for someone with a much faster cpu.

<font color=blue>_______________________________</font color=blue>
Asus A7N8X-X, Athelon XP 2500+ Barton,
Samsung 1gb DDR400, MSI GeforceFX5900 XT.
Aquamark=<b>36077</b> 3DMark03=<b>5322</b>
April 20, 2004 9:06:23 AM

He probably need a new PSU too...

Asus A7N8X Deluxe, Xp 2500+(3200+), 512MB RAM, HIS Radeon 9500Pro
April 20, 2004 10:11:53 AM

Oh I agree he won't get the full potential out of the card with his cpu, and probably all his other components too. But the full potential of the videocard means nothing if the performance increase is minnimal. If you got a top of the line computer and a mediocre videocard then your already going to be getting decent fps in most if not all games. So upgrading to a 6800 Ultra with such a highend system is going to give you fairly better fps percentage wise. However on a less then top of the line computer the upgrade from his videocard to the 6800 Ultra would, in my opinion, result in a more noticable performance increase in comparison.

<font color=blue>_______________________________</font color=blue>
Asus A7N8X-X, Athelon XP 2500+ Barton,
Samsung 1gb DDR400, MSI GeforceFX5900 XT.
Aquamark=<b>36077</b> 3DMark03=<b>5322</b>
April 20, 2004 12:29:02 PM

I will give you some fact based on my personal experience :

<b>Step 1</b>
CPU : P3-700MHz (OC to 770MHz)
GPU : GeForce 256 64Megs
3Dmark01 : about 3000

<b>Step 2</b>
CPU : P3-700MHz (OC to 770MHz)
GPU : Radeon 8500LE 128Megs
3Dmark01 : about 6000

<b>Step 3</b>
CPU : Athlon 1800+ (OC to 2400+)
GPU : Radeon 8500LE 128Megs
3Dmark01 : over 10000

You can clearly see that upgrading my GPU gave me a very good boost in 3DMark 2001, but I still got a lot of lag in cpu intensive games, then I upgraded my CPU (Step 3) and got another big boost in 3DMark 2001, but this time, my CPU intensive games were not lagging. You need a good balance between GPU and CPU. Top GPUs needs a very good CPU to be exploited to their maximum. Top CPU must be paired with a fast enough GPU to not "waste" their computing power.

If you have the money to buy a GeForce 6800 ULTRA, you will surely have the money to upgrade your CPU. Does your MB supports newer CPUs?

<b><font color=red>GO!</font color=red> <font color=blue>HABS!</font color=blue> <font color=red>GO!</font color=red></b>
April 20, 2004 2:27:01 PM

The easiest way to tell if you are limited by CPU or GPU is to test at different resolutions.

With non-CPU intensive applications the framerates will start ridiculously high but usually drop by the higher resolutions. If the framerates start out low and don't change no matter what resolution then that test (or game) is CPU limited.

For example with Q3 you might see 300 fps @640x480, 1024x768. Framerates might start to drop off at 1280x1024, say 220 fps, and then at 1600x1200 you might see only 100 fps (all just example numbers).

Take UT2004 on the same system. You might hit a framerate limit of only 40 fps (another example only) but it's the same at all resolutions. Doesn't matter high or low. This is being CPU limited.

Now in the latter example even though the CPU is limiting framerates this is not a constant number. The upper limit will change with a faster card. Performance will still be CPU bound (assuming the same system) but the ceiling will be raised. Perhaps instead of that 40 fps ceiling you now have 60 fps.

Over-simpified, there are always two components to graphics performance, CPU calculations and GPU rendering. Speed up one component or the other and you always get some benefit.

In your case, with a newer card I think you will get some framerate increases. At least at higher resolutions I think you will. You should get some new eye candy, plus be able to run AA at higher resolutions than you could before, and even run AA in some games in which performance was to slow to run AA at all.

How much gain you get I couldn't say but I think I can tell you a way to kind of guage what you might get.

In the old UT2003 (that's '03 not '04) you can edit the UT2003.INI file and select the NULL renderer (vs the D3D renderer). This completely takes the video card out of the equation. Benchmarking in this mode will tell you the absolute upper limit of framerates on you system (UT2003 only, of course). You need to use the UT2003 benchmark since there is no actual video going on to use with FRAPS. You can compare these "ideal" results with what you are actually see with your TI4400. The difference is the room for improvement.

Obviously you can't obtain the ideal (becausing rendering always takes SOME time) but the faster the video card the closer you get to the ideal. The numbers will give you an idea of what your current system is capable of and where you currently stand. Plus you can use those ideal numbers to compare with the actual numbers of better systems.

I wish more games had this kind of benchmarking.

<b>56K, slow and steady does not win the race on internet!</b><P ID="edit"><FONT SIZE=-1><EM>Edited by phsstpok on 04/20/04 10:45 AM.</EM></FONT></P>
April 20, 2004 2:29:37 PM

TOTALLY depends on which game you're running.

<b>Radeon <font color=red>9500 PRO</b></font color=red> <i>(hardmodded 9500, o/c 340/310)</i>
<b>AthlonXP <font color=red>~2750+</b></font color=red> <i>(2400+ @2.2Ghz)</i>
<b>3dMark03: <font color=red>4,055</b>
April 22, 2004 8:32:13 PM

Thanks for all the input. Looks like it comes down to when I expect to upgrade other parts. If I had a 533 FSB MB, I would get a 2.8 or something, but the fastest 400 FSB processor is a 2.4, I think. Doesn't seem worth it to me. Maybe a 6800 (non-Ultra) sounds more reasonable for me. I would like to try Far Cry, which is why I'm asking. I recently upgraded my PSU to 465, so I should be okay in terms of power.
April 22, 2004 10:42:09 PM

You should be able to play FarCry on your system as it is. Even on the lowest settings the gamee looks pretty dang nice.

<font color=blue>_______________________________</font color=blue>
Asus A7N8X-X, Athelon XP 2500+ Barton,
Samsung 1gb DDR400, MSI GeforceFX5900 XT.
Aquamark=<b>36077</b> 3DMark03=<b>5322</b>
April 22, 2004 11:44:47 PM

You will never be able to keep up with technology. That’s the bottom line. There is no way you could buy/build a new systems today that kicks a** and have it still kick a** in 2 years (youll mostlikely want to upgrade something in at least 1 year). Technology moves to fast. If you buy that card now, 6 months to a year from now you be SOL because pci express will be out and youll have to upgrade the whole system and the video card will be useless ( unless nvidia makes that converter thing their talking about). Wait till the card comes out. See if it’ll keep you happy for a while and be compatible with anything new that you want to buy and do lots of research.