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Can Someone Please Explain CPU Limiting Please

nheather

nheather

nheather

Associate
Joined
19 May 2004
Posts
1,037
Location
Horsham, West Sussex
My current setup is

Core 2 Duo E6750 - OCed to near 3GHz
8800 GTS 320MB - Stock
2GB 1066 RAM
Windows XP
1280x1024 monitor

The latest games (ARMA II) are struggling so all suggestions are that the GFX is the problem so I'm going to upgrade.

Wise men say that a 4850 or 4870 512MB would be more than ample but since the prices are so close and I don't want to get into the DX11 stuff I figure I'll get a 4890 1GB.

Now I've just read other posts about a guy in a similar position being told that his CPU will be the limiting factor if he gets a 4890, maybe even if he gets a 4870.

This is where my knowledge begins to fail me.

I understand that my CPU is Duo Core and that there are Quads out there - but from what I can see the Cores run at about the same speed as mine unless I want to spend silly money.

But there are more cores, so they can do more work - I understand that but from what I've read hardly any games make much use of any more than one core - if that is the case surely the game will run pretty much the same with a single 3Ghz core as a quad 3GHz core.

Am I missing something - can someone explain.

For example - there is a good offer on the Q9450 at the moment but this runs at 2.66GHz same as my E6750 - so would Q9450 be a noticeable improvment for playing games?

Cheers,

Nigel
 
No, I've pushed the CPU to around 2.8-2.9 but no more.

Not OC'ed the GTS at all and won't bother because I'm definitely getting a new graphics card.

It was just the posts I'd read about CPU limiting that got me worried\puzzled.

Cheers,

Nigel
 
Hi,

In games I believe you will get a slight improvement if using the Q9450. Not leaps and bounds better but a few FPS and the feeling of smoothness. In every other aspect apart from gaming though the Q450 will monster your current CPU.
I feel you should not really be restricted by your current CPU when gaming. If you can clock that a little more id say you have nothing to worry about , especially if you look at a 4890.

Worse can senario , you just buy the 4890 and find the cpu holds you back ( personally i dont think so ). You then know for sure you need another CPU. You then save for a higher clocking Dual or Quad.

McT
 
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Many thanks - that's what I was intending - do the GFX card now and upgrade the rest later if needed.

But to be honest it is only with games that I have felt the need to say "my computer could be faster" - email, and microsoft office run fine - internet could be faster but I don't think the CPU will help there.

Cheers,

Nigel
 
nheather said:
Core 2 Duo E6750 - OCed to near 3GHz
8800 GTS 320MB - Stock
Motheboard ????
2GB 1066 RAM
Windows XP
1280x1024 monitor
Click to expand...
Hi Nigel,

What motherboard are you running? it better be really bad otherwise you have no excuse to not be running your Intel® Core™2 Duo E6750 at 3.2GHz (8x400), at that speed you should have no issues at all! :cool:

Fast CPU MHz is important when running a full-on game, it has to feed the graphics card with data, work out the Ai and generally shovel data backwards and forwards across the system.

To get the best out of the latest GPU's you need to give it enough CPU processing speed and as much Memory bandwidth as possible. I don't think a fast Dual-core has any problems running games once it reached around 3GHz. You may find 2GB of system memory causes an occasional Stutter during a game when the system has to use the page file but it will still work . . . . . 4GB of memory should give you more than enough system memory to avoid any slight stutters! :)

CPU Limiting really only applies to Older CPU's and to systems with Two/Three Killer GPU's installed . . .
 
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There's a fairly detailed account of ArmaII performance with different video cards here: http://www.hardocp.com/article/2009/08/10/arma_ii_gameplay_performance_image_quality/

Looks like one pretty demanding game. Even very high end graphics cards can't max it out. We might be looking at the new Crysis here...

Edit: They briefly cover CPU and memory usage. It used 69.5% of a quad core at peak. Most load on one core with the rest of the load spread evenly across the other three. That suggests to me that it's been optimised for multi-core. A triple or quad core CPU will probably offer benefits over a dual core.
 
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you have a small monitor a small res will put the bottleneck more on your cpu.

upto maybe a 4890 your cpu woluld be fine with higher res (1680 or above) at your current res i would say it would still probably do it.
 
Most games will run significantly faster (up to ~75%) on a dual core than single these days, and several will get another 20% going to quad (If all CPUs are compared at the same clock speed).

Many games are designed with consoles in mind these days, and they tend to have more than 2 CPU cores, so the sweet spot is probably 3 cores at the moment.
 
I don't think that CPU will be a bad bottleneck with any cuurrent GPUs, although that may be a different story when AMD release teir next lot.
 
manic111 said:
I don't think that CPU will be a bad bottleneck with any cuurrent GPUs, although that may be a different story when AMD release teir next lot.
Click to expand...

I disagree. With a 4890 at the OP's low res then the cpu will be the bottleneck.

However, the 4890 will be a big boost over his current card although it won't be running near its max performance.

Just to clarify, even with modern cpus and contary to Big Wayne's post, you will find that at 1280 x 1024 res, the cpu will hold back the full potential of even a 3ghz dual core cpu.

Say the OP is only getting 20 fps with his gpu. A 4890 might give him 50 fps which is a major boost and is more than enough but with a faster cpu he might be able to get 70fps. (made up numbers btw, just as an example)

A few articles here.

http://www.guru3d.com/article/cpu-scaling-in-games-with-quad-core-processors/1

http://www.legionhardware.com/document.php?id=770&p=8

Notice in the last one that although its a faster card (4870x2) than the Op is planning to get, even at 1900 x 1200 res which should really be gpu dependant, each 200Mhz increase in the cpu leads to healthy fps gains of over 5% each jump and continues all the way to 3.6Ghz.

Personally I suspect to make the game max out at 1280 x 1024 with a 4890 you would need a 4Ghz cpu.
 
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yep tried it out to test from 2.0 with a dualcore and upto a 3.4 quad

you want at least 3.0 ghz and at least a res of 1680 even at 3.2 quad my mate noticed a little bottle neck on his 4870x2

so maybe new monitor should be on the cards aswell.
 
Greebo said:
you will find that at 1280 x 1024 res, the cpu will hold back the full potential of even a 3ghz dual core cpu
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That doesn't make sense! :D

Greebo said:
although its a faster card (4870x2) than the Op is planning to get, even at 1900 x 1200 res which should really be gpu dependant, each 200Mhz increase in the cpu leads to healthy fps gains of over 5% each jump and continues all the way to 3.6Ghz.
Click to expand...
I was talking about a single GPU set-up Greebo!

Your using 3rd party information based on testing with *Wildy* different hardware configs with a large difference in FSB and Memory Frequency!


legionhardwaregpuscalin.gif


Greebo said:
Personally I suspect to make the game max out at 1280 x 1024 with a 4890 you would need a 4Ghz cpu.
Click to expand...
If Nigel gets his chip running at 3.2GHz (8x400) and combines it with a HD4890 and games at 1280x1024 he will have zero issues and will be able to get great framerate . . . . . he doesn't need to worry about CPU limiting! :cool:
 
Do you see ArmaII in those benchmarks?

Whether or not a graphics card is CPU bottlenecked is generally game dependent. GTA IV, Arma II, Supreme Commander and a number of other titles certainly benefit from Quad core over a highly clocked dual core.
 
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Uriel said:
Do you see ArmaII in those benchmarks?
Click to expand...
No I'm just showing the results that Greebo is basing his statement on! :)

Now Uriel can you please delete my quote in your post please, there is no need to quote my entire post as the original is just above yours! :p
 
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