Should i overclock? Is the CPU my bottleneck?

Hi! On Wednesday i bought all the parts for a new computer, and put it together, everything except SLI worked just fine.

First, system specs.
HDD: Seagate Barracuda 7200.10 320GB SATA2 16MB 7200RPM
CPU: Intel Core 2 Duo E6600 2.4GHz Socket LGA775, 4MB
RAM: Corsair TWIN2X 6400 DDR2, 2048MB CL5 Kit w/two matched CM2X1024A-6400 Dimm's
GPU1: XFX GeForce 8800GTX 600M 768MB XT GDDR3 ,PCI-Express,2xDVI/HDTV/HDCP,600/1900Mhz
GPU2: XFX GeForce 8800GTX 600M 768MB XT GDDR3 ,PCI-Express,2xDVI/HDTV/HDCP,600/1900Mhz
MOBO: XFX nForce 680i SLI, nForce-680i SLI, Socket-775, 2xGbLAN, DDR2, 2xPCI-Ex16
MONI: Videoseven 19" LCD R19W11 TCO-03 Silver 1440x900,5ms,700:1,VGA
PSU: NorthQ NQ-4775-1000 Giant Reactor, 1000W 8xSATA, ATX/EPS, 4xPCI-E, 20/24pin
OS: Windows XP Home Edition


Everything is connected where is should be, and everything fits perfectly. I've also checked each card alone, to check if there was something wrong with any of them. Gpu 1 in slot 1 with power wire (?) set 1, gpu in slot 2 with power wire set 1, and so on and so forth.

I also have the latest drivers for chipset, GPU and the latest direct x version, and everything seems O.K with them. The settings is also configured right.

So here's my actual problem:
When i enable SLI in nVidia control panel, i get slower fps/performance in all games, compared to just using a single GPU (or SLI disabled in nVidia Control Panel). I'm using AFR1, because AFR2 and SFR makes it even laggier.

I've talked with a lot of people on different forums, but none seem to come up with an answer i don't already know.

At last, the questions:
Is this the CPU bottlenecking the GPU's working together while using SLI? Or is it something else? If it is the CPU, should i overclock with my current rig? Would it be smart?

Other notes:
I have a G15 keyboard which shows how much of the CPU i am using, and when i play games, it never reaches 100%, can it still bottleneck the GPU's?


In advance, Thank you.

Kwante, from Norway.

Hey, thanks !

First of all, i'm not overclocking. so that wouldn't be a problem, i will post the FPS ASAP, but right not i cant use the computer for about 2 and a half hour, my brother uses it for school work. Anyway, as far as i remember the fps in I.E. Oblivion, with one card, is around 50-90 fps, all settings maxed. Which is awesome IMO. When i use SLI, i fall down to 30-50. Note: This just happen when i switch settings in nVidia Control Panel. Even though i switch back to default setting, i get bad fps. The only way i can get back the good fps (which is the fps i get while using 1 card) is to disable SLI, and restart the computer, then enable SLI again, restart, and then i have the exact same FPS as i usally have (50-90).

You said i should disable those things in BIOS, and i will try that, i remember seeing Graphics EX. on.


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I got my brother of the computer, and tried what you said, nothing worked sadly. I disabled Nvidia GPU EX. And put all the PCIe ports to 105mhz. Shall i try the other mhz's between 100 and 105 too?
For now, I'm going to test out each GPU in diffrent places, switching cables etc. again. If that doesn't help, I'm starting to think there is something wrong with the SLI bridge itself. It would explain a lot, although, if it were actually ruined, shouldn't i crash or the games wouldn't start or something when i try starting a game? Maybe it's partially damaged. <(o.O)>


Kwante

Don't quite understand exactly what settings are where. Are you making your graphical changes (AA/AF/whatever else) inside of the Nvidia control panel or in the Oblivion options menu? Or is the only thing you are changing in the Nvidia panel the SLI toggle?

Lastly, is the SLI setting staying when you restart, or do you turn SLI on again each time you start up.

Also, try running a synthetic video benchmark to test out after each change, it might be a bit easier than running a game each time. Just take the reading, enable SLI, take the next reading. Might as well limit the amount of things that might be going wrong at any given point.

You lost me here... You have two 8800GTXs, each of which has 2 6-pin power connectors. You have each of the four power connectors hooked up to a different rail, right? Just because a single rail has two 6-pin connectors doesn't mean it supplies the correct current. This could lead to a real drop below required power.

EDIT: Nevermind, just looked up the power supply. No way to make a mistake there.

lol, nice work! i'm glad you got that figured, lol, on my computer i chose to gt the thermaltake 1200W for 3 reasons, 1) i could basically plug anything in any where and it would get enough power and 2)it was the only 1200W i could get in aus at the time and 3)it should be plenty for the future.

You already have more than enough horsepower to eat up anything as it is,IF I were you I would be quite content just to get that BEAST up and running reliably for at least a few months and to get to know the whole system working together BEFORE I EVEN thought of pushing it at all,,,,,,,,,
remember about "leading bleeding" it's mostly bleeding.

Enjoy what you have,get to know it well under all conditions,then get out and push the hell out of it...Have phunn..

uh.. so you mean I'll just let the 8800 GTX lie in the shelf and get dust on it? O.o i want SLI when i've payed for it.. and obviously there is a hardware faulty, so the company i bought the parts from are the one who's gonna fix this problem.. I just need to know WHAT part is ruined. GPU, PSU or MOBO?

I mean there's an extra 4-pin power connector on the motherboard right next to the blue IDE (harddisk/cdrom) plug. It's a little black plug to the right of the memory slots at least according to the online manual. Maybe you have a different version?

ooopps noticed you have XFX will have to see if that´s the same.

k, more good news, tried both power cords, and reseated the gpu again.. still laging.. so since i dont lag with the other card, its iether the gpu (most likley) og motherboard.. now, its time to test the gpu in another slot a few times.. if it lags there, its the gpu, if not.. well then its the motherboard..

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Don't know if it's good news, but it is at least news:
GPU 2 works just fine in slot 1, but sometimes (yes not all the times) it lags like hell in slot 2.

If this was it, it would be easy, but there is more. GPU 1 doesn't lag at all in slot 2, ever. Its ONLY gpu 2 which lags in slot 2. Why?

So what is wrong? GPU 2 or the motherboard?

(I feel we're uncovering some murder.. but at least I/we make progress..)

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For those who still care (if any), i have returned the gpu's and the motherboard to the company i bought the parts from, but they say everything works fine!.. /sigh

Any other factors that can make SLI not work? Malfunctioned SLI bridge perhaps? The ram?

Yea, i've tried that combo too.. but, you mean the psu, even though it's 1000w doesn't cover my sli? It doesn't make sense to me.. power is power.. right?

I see. I'll remember what you say. But first I'm just gonna wait for the package to get back to me from the company that checked the parts. If they for some miracle works, I'll be really happy. But i doubt that.

You wouldn't happen to know if the company are obliged to take back the ware because it doesn't work with my system, do you?

One more thing, I've checked around on the net about my PSU, and you said it's only tier 4, but that's a different PSU, it's 500W, and got a bad score in many reviews! But the one i have, have great score everywhere. So it's hard to actually imagine it's the PSU, but I'll not discard the idea.