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SLI question concerning cpu bottleneck

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October 4, 2008 8:35:04 PM

okay guys i'd like to increase graphic performance and am considering SLI with the current computer specs.
windows XP 64bit
antec 900 case
EVGA nforce4 sli mobo
cpu- S939 4600+ X2 oc'd to 2.6ghz sable (will not go higher, i am limited by my mobo not wanting to accept higher FSB than 217)
gpu- 9600 GT @ 700 core 1000 mem
psu- 700w OCZ gamextreme
ram- 2 gb ddr 400


i am currently gaming at 1440x900 max res. and i like to turn everything up that i can.
i would like some input about if SLI'd 9600s sill be bottlenecked very badly with my CPU
a b U Graphics card
October 4, 2008 8:53:58 PM

your cpu will slightly bottleneck 9600gt a little bit, but dont worry about it.
October 4, 2008 8:55:59 PM

thank you.
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a b U Graphics card
October 4, 2008 9:07:14 PM

It looks like you are badly bottlenecked by that 939, the good news is AMD products are in "Fire Sale" mode. So you can easily pick up a new MB, CPU, and RAM for about $300.

IE:

MB: http://www.newegg.com/Product/Product.aspx?Item=N82E168...
$145 (GA-M750SLI-DS4)
CPU: http://www.newegg.com/Product/Product.aspx?Item=N82E168...
$100 (Phenom 8450, tri-core)
RAM: http://www.newegg.com/Product/Product.aspx?Item=N82E168...
$53 (Patriot 2x2GB DDR2 800)($20 MIR)

Total: $298 + S&H, or you can get a core 2 system

MB: http://www.newegg.com/Product/Product.aspx?Item=N82E168...
$150 (Asus P5N-D)
CPU: http://www.newegg.com/Product/Product.aspx?Item=N82E168...
$120
RAM: same as above $53 (with $20 MIR)
October 4, 2008 9:42:02 PM

as in i am bottlenecked already with my current setup? i would prefer not to have to upgrade the rest of my system. i am getting mixed reviews here.....can i get some more opinions PLEASE!!!
a b U Graphics card
October 4, 2008 9:55:43 PM

Youll get some bottlenecking, but it wont be that bad, as your gpus wont see too much, and going sli will really improve your fps
October 4, 2008 10:03:33 PM

okay so a new 9600gt it is then, what if i don't have the SLi dongle?
October 4, 2008 10:23:17 PM

hemir1 said:
okay so a new 9600gt it is then, what if i don't have the SLi dongle?

I guess you'll have to get one :p 
a b U Graphics card
a b à CPUs
October 5, 2008 1:47:31 AM

Dude, don't SLI those cards XD

The PCIe bridge of the nF4 will gut rip it out, remember it's PCIe 1.1 x8 when you get SLI working. Try getting a bigger card on the single PCIe, will hurt less IMO. Think about a 9800GTX+ or a 4850.

I got a 4850 and it's only bottlenecked on CPU demanding games (CPU physics mostly -> Crysis), but everything else is NOT bottlenecked over 1280x1024. Read my sig, my system is very close to yours.

Esop!

EDIT: Spelling XD
October 5, 2008 3:01:22 AM

what do you mean gut rip out? i will be spending about 60-80 dollars more upgrading to a 4850 too....also won't 2 9600gt's be faster than a 4850 anyway?
October 5, 2008 3:24:23 AM

I would not recommend to you to SLI those cards with this CPU.

I had one a few months ago running a single 7800GTX. Life was great until some of the new games came out. Back then the 8800GT was the king of the hill (performance/money-wise) and I switched my 7800GTX by one of those.

It ran nice, but then I added another 8800GT. Boy, shouldn't have done that. Overall my performance increase was about 10-15% over single card setup.

Given that, I did a total overhaul on the system and went to a new 750i chipset with a E8400. Then I realized how my old X24600 was holding me back. The single 8800GT with the E8400 was faster than the SLI setup in the 4600.

Cutting it short, I would strongly advice you to upgrade the MB/Processor before moving forward. The socket 939 can still be very good for office/web/etc stuff, but for gaming is showing its age by now.
a b U Graphics card
a b à CPUs
October 5, 2008 4:01:01 AM

vmardegan said:
I would not recommend to you to SLI those cards with this CPU.

I had one a few months ago running a single 7800GTX. Life was great until some of the new games came out. Back then the 8800GT was the king of the hill (performance/money-wise) and I switched my 7800GTX by one of those.

It ran nice, but then I added another 8800GT. Boy, shouldn't have done that. Overall my performance increase was about 10-15% over single card setup.

Given that, I did a total overhaul on the system and went to a new 750i chipset with a E8400. Then I realized how my old X24600 was holding me back. The single 8800GT with the E8400 was faster than the SLI setup in the 4600.

Cutting it short, I would strongly advice you to upgrade the MB/Processor before moving forward. The socket 939 can still be very good for office/web/etc stuff, but for gaming is showing its age by now.


Then you're proving my point. SLI isn't worth on a nF4 by today's standards. I mean, not price/perf wise. You'll still see an FPS increase, but it won't be what you would expect.

The x8 PCIe 1.x link they have (equivalent to a x4 2.0 i think) will indeed handicap very bad the data throwoutput of the cards. Maybe the processor can keep up, i'd say yes it can, but RAM wise and Bandwith wise, it won't.

That's why a single card solution is the best you can get and not get dissapointed IMO.

Esop!
a b U Graphics card
October 5, 2008 4:20:13 AM

That may be true, as I didnt notice his board (my mistake). Got to remember tho, the 9600s are less powerful, lower BW I believe as well, so the falloff might not be as bad.
a b U Graphics card
a b à CPUs
October 5, 2008 4:36:47 AM

Uhm... I don't know JDJ... It's a DDR400@434Mhz MoBo with a HT1.0 link we're talking about here...

He's already pushing his whole bandwith for 1 card alone, and asking that same bandwith to cope with 2x cards is a really hard thing to achieve for that system.

Like i said, he'll notice a FPS increase, but by all means it won't be a 90% increase, i'm betting not even a 20% on any res bellow 1680x1050. That's not anywhere near "bang for the buck" in my vocabulary. He'd better save that price difference and get a single card solution. He can even try and sell his card to get 1 9800GTX+/4850.

Esop!
October 5, 2008 4:58:07 AM

actually with 9600gt sli, i get some bottle from my stock q6600.

the 9600 is one of the best sli scaling cards out.

let alone on a stock q66, i saw increases up to 35-40% in the games i play.

and i got even more when i OC to 3.6
a b U Graphics card
October 5, 2008 4:58:43 AM

Ill take your word on it, its still good right? heheh. If the board bottlenecks like that, then no, its a no buy, and to use the single card approach is definately preferable.
October 5, 2008 5:18:09 AM

okay so basically i don't want to upgrade gfx cards at all, and i'll just stick with what i have already(yes or no??). if SLI'd 9600 GT's will be bottlenecked severely, then can i draw a conclusion that a more powerful card like a 4850 will too!?!?(yes, no?)
a b U Graphics card
a b à CPUs
October 5, 2008 5:26:50 AM

Not like a SLI solution, not.

It will be bottlenecked, yes, but not like the 2 9600's at the same time on your board. Why? Bandwith doubles from 2 cards to 1.

If you have only 1 card on board, the PCIe link stays at x16, if you go SLI, it goes x8, plus your RAM/CPU has to do close to double work to feed those cards.

With a single solution, the card that you have will get the whole CPU/RAM bandwith for itself, being less handicaped.

So yes, you *could* say that a single 4850 won't be handicaped compared to 2 9600's in SLI.

Esop!
October 5, 2008 5:31:27 AM

in GPU-z it is showing x16 PCI-express @x8....what is this about
October 5, 2008 5:50:28 AM

okay, a little research tells me that i need to plug my single card into the middle PCI-express slot instead of the first, as the two of the same color are x8 slots for SLI and the middle is X16 for single card operation. is this true and am i limiting FPS in games right now as it is??? i get about 850fps in ATITOOL right now if that can be used as a gauge and about 35-50fps with max setting in Bioshock @1440x900 and about 30-35fps in Crysis at med-high settings @1440x900
a b U Graphics card
a b à CPUs
October 5, 2008 6:27:28 AM

In single card, maybe not that much, but i can tell you that you're not feeding your card at it's max right now.

Since you play at a low res, i can't tell you first hand that going to x16 will boost 100% more, but it will indeed boost a little more, maybe 10%-20% from your current scenario.

Give it a shot and tell us later, u'd be giving us a better look of how the Athlon64's handle that x8 to x16 in the old PCIe 1.x.

I'll keep an eye on this :D 

Esop!
October 5, 2008 6:57:55 AM

okay guys here goes.....at full x16 now and using atitool fps generator and fraps to monitor in a few quick games, i get no diff. in fps at all..does this change any opinions about SLI or at least new theories about if i can get a benefit out of it?
a b U Graphics card
a b à CPUs
October 5, 2008 7:08:45 AM

The only thing i can conclude is that 1440x900 doesn't require a lot of bandwith and/or your card is indeed being bottlenecked by the CPU alone.

Sorry for the crappy conclusion xP

Crank up the details and see how it goes. I'd say you should note a difference there.

Esop!
October 5, 2008 7:15:08 AM

an athlon 64 x2 @2.6 bottlenecks a single 9600GT?? or 9600GT doesn't need more than PCIe x8 bandwidth? i appreciate all the opinions and help i'm getting on this too....anybody care to give me any concrete info on this subject?
a b U Graphics card
October 5, 2008 12:28:18 PM

stranger is telling you to test if your cpu is bottlenecking your card. Do what he suggested, and youll know if it is. I didnt think a 8x would bottleneck that card. Some of the highest cards I recall it definately does a lil, tho not much, but wasnt sure about cf/sli. So, if its not a top card, I guess not?
October 5, 2008 3:15:06 PM

okay i'll test and get back
October 6, 2008 11:31:33 PM

okay i just tested Bioshock and with all high i get 40-60fps and with all low settings and same res i get about 170 fps....what does this mean?
a b U Graphics card
a b à CPUs
October 7, 2008 12:02:10 AM

No, no... You have to test this: same detail, different resolutions; 1440x900@Max Detail, 1024x768@Max Detail, 800x600@Max Detail, etc... I don't know lower res on a wide, so use yours XD

If you go down on resolution and DON'T get higher FPS, then it's a clear bottleneck.

Esop!
October 7, 2008 12:35:55 AM

okay i just did the test over and i got a bit better perf. this time for some reason at 1440x900=50-70fps and at 640x480+100-200fps.....what does this mean???
a b U Graphics card
a b à CPUs
October 7, 2008 12:53:28 AM

That was on Max detail, right? AAx4, AFx8 and things like that?

Then your Video Card is not being bottlenecked by the Athlon, wich doesn't surprise me XD

Then getting another 9600GT shouldn't be held back CPU wise. But i'm still wondering about bandwith wise :p 

I still say: sell that 9600GT and get a 9800GTX/4850 instead of the second 9600GT if you can. It still won't be hard bottlenecked and it will have the x16 PCIe for it self (instead of sharing the x8 (x4 PCIe 2.0) in SLI).

Esop!
October 7, 2008 1:45:33 AM

there wasn't a place to modify AA or AF but it was max detail....still same recommendation?...spending $90-100 is easier than almost twice that as far as a diff. upgrade path.
a b U Graphics card
a b à CPUs
October 7, 2008 1:50:22 AM

If you can't then, get the second 9600GT.

I hope i'm dead wrong for your own benefit =/

GL mate!

Esop!
October 7, 2008 1:54:19 AM

dead wrong about what?
a b U Graphics card
a b à CPUs
October 7, 2008 2:09:53 AM

About scaling... I was telling you i wasn't sure if 2 of those will actually give you a "big boost" like you'd hope for.

Esop! XD
a b U Graphics card
a b à CPUs
October 7, 2008 6:04:59 PM

But if you lower the graphical details, you're not using the CPU also... Less textures to load, less memory allocation, less bandwith used.

You must pick up a certain detail level and run it on different resolutions and see if there's a noticeable difference (this case) or just no difference at all (bottleneck). I agree (now that i think about it a little deeper) that using max detail is kinda dumb, but keeping a certain lvl of detail above lowest, is indeed needed.

Esop!
a b U Graphics card
a b à CPUs
October 7, 2008 8:10:46 PM

No damage here, dude XD

Anyway, it's been on my mind this little topic... And i've come to the conclusion that both serve to different things: fixed res and variable details is more CPU benchie; and on the other hand, fixed detail and variable resolution is a mixture of CPU and overall system benchie.

I went there cause of how most ppl OC:

On almost all platforms there's the FSB thingy, commonly affecting RAM and CPU => bandwith + raw processing. Unless the board has a differente FSB ratio and all... But my typical scenario is that. People see a lot of improvements with the mixed FSB ratio on games when the bandwith is saturated, even if the CPU can keep up actually (DDR2-533 vs DDR2-1333 for example).

I remembered my own experience with the X1800XL, it wasn't being bottlenecked by anything on my PC. I OC'ed it and almost no change in FPS, but with the 4850, if i underclock, or just go back to stock, there is a noticeable FPS drop.

I hope TGGA comes and tells us "u're so friggin wrong" and show us the truth, lol.

Esop! XD
a b U Graphics card
October 7, 2008 9:41:08 PM

You 1800 was the bottleneck. No matter what youd do, it was giving all it could. The cpu was getting more out than your gpu. Now, with your 4850, its the other way around. Your cpu is slowing your gpu down, and the cpu cant compensate at all for it. I tried telling the guys in the cpu section these things and they say no gpu can be faster than a cpu. Times have changed, as gpus have begun to outpace cpus
a b U Graphics card
October 7, 2008 9:53:46 PM

Weve all seen benches that show the first 2 or 3 res at almost the same fps, but as you go up, the fps drop, or thus, a cpu "bottleneck". Think of it the other way around now. There is no up. All are the same fps or close. Thats also a cpu "bottleneck", as all res max out fps. The first one I mentioned "bottlenecks " the cpu because the res is so small the gpu has no work to do to keep up, and everything is dependent on the cpu. The secong one, or where all fps seems the same at all res, is where the gpu is too powerful for the cpu at all res, BUT, if you oc your cpu and the fps goes up, then theres your proof, and the higher your cpu oc is, the higher the fps are. Its the other way around in a way, and it hasnt happened really in the past, it just now is starting to happen
a b U Graphics card
a b à CPUs
October 7, 2008 10:04:41 PM

But "fast" is a hard thing to explain also...

If we talk about "fast" in terms of cicles per second (frequency:Hertz:Hz), yeah, a CPU is faster all the way. It can execute in several ways also a single instruction and it can do like 3 things according to the states and blah blah blah...

If we talk about "fast" in terms of "things you do per cicle" (FLOPS for instance), it's the other way around. GPUs are parallel kind of processors (that's why Larabee has 20+ cores), but with a different way of doing things. So if you can find things that can totally be done in parallel, the GPU is going to own the CPU (or maybe the other way around) according to a relation of threads/speed. If you have a 'thing' you can't paralellize and it will only use 1 thread no matter what, the CPU is going to blow the GPUs arse off the window, but fortunatly for GPUs, all things are mathematical operations and a LOT of them can be paralellized.

We say "OMGzz, CUDA iz da thingz", but we have to remember that CPUs, in a long part of computer's history, has been doing GPU things, but on minor scale, off course (Software Rendering). Now we find ourselves in a threading world, were (maybe) by coincidence, GPUs happened to be faster than CPUs because of the way they work with OpenGL (matrix operations)

So you tell me, what's "fast" for you and i can agree or totally disagree with you my dear JDJ :p 

Wow, off-topic warning next time folks! Sorry XD

Esop!
a b U Graphics card
October 7, 2008 10:33:42 PM

Fast is relative, as youve explained. Fast means doing something within accepted time. But faster, now theres the thing. When one component is "faster" than the other, all it means is, its finished with its work before the other component has. Thus, a slowdown, or "bottleneck". Like you inferred, some games require more from your cpu than others. Of course, the majority of a games work relies upon the gpu. But think like AI or phisics rely on the cpu, tho physics is now being implemented on the gpu as well. If we see at all resolutions a common fps, we can usually determine the rig is cpu "bottlenecked", just like at low res, you see no improvements, except this time, no matter how high the resolution, the gpu isnt pushed enough to do more, and had to wait on the slower cpu, but as we crank the oc on the cpu up, we start to see fps increases across all resolutions. Its just in the past, weve always had higher resolutions to go to that weve seen the bottleneck, but with todays cards, its getting to the point where even at 19x12 in alot of games, cpu are the slowdowns in your rig with a top card, and even some 25x16 games we see it.
October 7, 2008 11:19:38 PM

vmardegan said:
I would not recommend to you to SLI those cards with this CPU.

I had one a few months ago running a single 7800GTX. Life was great until some of the new games came out. Back then the 8800GT was the king of the hill (performance/money-wise) and I switched my 7800GTX by one of those.

It ran nice, but then I added another 8800GT. Boy, shouldn't have done that. Overall my performance increase was about 10-15% over single card setup.

Given that, I did a total overhaul on the system and went to a new 750i chipset with a E8400. Then I realized how my old X24600 was holding me back. The single 8800GT with the E8400 was faster than the SLI setup in the 4600.

Cutting it short, I would strongly advice you to upgrade the MB/Processor before moving forward. The socket 939 can still be very good for office/web/etc stuff, but for gaming is showing its age by now.


:o  *Drool*

Good to hear, Ive got an E8400 and SLi board showing up tomorow or Thursday to replace my Opty 165 runnin 2.9Ghz w/ SLi 8800GT. :bounce: 
a b U Graphics card
October 7, 2008 11:34:29 PM

Let us know how it goes. My old opty 185 is slowin its age (no typo
offended)
October 8, 2008 2:44:10 AM

Yea, Im gonna collect some benches, its a 650i board, so I should be able to tell if the 8x links are/arn't a bottleneck.
October 8, 2008 3:47:23 AM

okay guys, interesting thread and all, but from other research i've done on the "net"and my own tests. i have found that the 2-x8 lanes aren't going to be the slowdown if i go to SLI w/ 9600gt but the CPU may be. i would appreciate a final concensus on if i will be bottlenecked by the cpu based on my earlier posts of my avg. fps using bioshock as the benchmark. and if so how much of a bottleneck, based on opinion of course, big or little or if any. thanks in advance to your replies.
a b U Graphics card
October 8, 2008 11:26:14 AM

OK, just as I thought, the 8x doesnt play as big a role on lessor cards. Ok, Id say youll see a small amount of "bottleneck" from you cpus, not alot, but itll still be there. It wont be as noticeable as some may claim, mainly because youre at 2.6. If youre at 2.2 or less, youd see some bad results. Going on older knowledge, a 2.2 K8 could max out a 1950xtx. Being you cards is about 30% faster, your oc on your cpu is only 20% or thereabouts over 2.2, so, as Ive said, youll lose some, just not too much as you wont see alot of improvement. Let us know, but thats my HLO
a b U Graphics card
a b à CPUs
October 8, 2008 7:30:25 PM

JAYDEEJOHN said:
OK, just as I thought, the 8x doesnt play as big a role on lessor cards. Ok, Id say youll see a small amount of "bottleneck" from you cpus, not alot, but itll still be there. It wont be as noticeable as some may claim, mainly because youre at 2.6. If youre at 2.2 or less, youd see some bad results. Going on older knowledge, a 2.2 K8 could max out a 1950xtx. Being you cards is about 30% faster, your oc on your cpu is only 20% or thereabouts over 2.2, so, as Ive said, youll lose some, just not too much as you wont see alot of improvement. Let us know, but thats my HLO


Was that single card config or Cross Fire? :p 

Esop!
a b U Graphics card
October 8, 2008 8:13:03 PM

That was single card, but having a lower card makes less and less difference, but again, how much no one knows, as they just do articles/benches on this. Same with a AMD cpu vs a Intel cpu. At a certain point, your card matters more than your cpu and vice versa, but no ones done this. My guess is of course 2 cards need more juice than 1, but how much? I do recommend quads for a dual card setup, whether its a sli/cf or a x2, tho a dual with lessor cards? Who knows how performance sits? Anyone have benches?
a b U Graphics card
a b à CPUs
October 8, 2008 8:29:20 PM

I know this: At higher resolutions, you need a LOT of bandwith on the PCIe lanes to keep the data flow with no hiccups.

On the PCIe 1.1, TH did some tests to know if there was a performance hit lowering the multi of it: x16 to x1 (i think). If i recall correctly, the result was the thing i stated above.

They didn't do it on SLI nor CF, but the logic should be the same, since when we talk about system bandwith, that's a CPU-RAM-PCIe thing and not a video card thing.

Only top notch video cards are usually limited in terms of CPU processing. And with older systems, it's more a bandwith issue than a CPU issue, but it's always a mixture.

I'll look around for that and post it.

Esop!
a b U Graphics card
October 8, 2008 8:53:17 PM

TY, reading it now
!