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PCI express freq to 100mhz? or Auto?

Last response: in Overclocking
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May 10, 2008 4:56:34 PM

So after reading the overclocking guide they mentioned if you overclocked your CPU which will be most likely make the FSB higher (in my case from 333mhz stock to 400mhz), you also have to set the PCI express frequency to 100mhz instead of Auto in the bios? so that you won't burn the graphic card . Or is it still ok if I just leave the PCI express frequency at "Auto" in the bios?

Asus P5K/EPU board
E6750 at 3.2ghz (400mhz FSB)
2G Crucial Ballistix Memory 5-5-5-18 (2x400mhz = 800)
a b à CPUs
a b K Overclocking
May 10, 2008 5:18:54 PM

Set it to 100Mhz.
May 10, 2008 5:24:00 PM

will this slow down my system performance like in games if i set it to 100mhz?
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May 10, 2008 5:26:36 PM

I set mine to 120mhz. Is that a bad thing?
May 10, 2008 5:35:26 PM

jincuteguy said:
will this slow down my system performance like in games if i set it to 100mhz?


Not likely if you are OCing. I have mine set to 33.33MHz and my frames have actually increased (obviously due to the increased processor speeds).
May 10, 2008 7:03:07 PM

I dont think I can set the PCI express to 33mhz, minimum is 100 man so I think u talking about the PCI normal port like for sound card , NIC card.
May 10, 2008 7:32:40 PM

stabgotham said:
Not likely if you are OCing. I have mine set to 33.33MHz and my frames have actually increased (obviously due to the increased processor speeds).

33.33MHz for the PCI. 100MHz for the PCI-E. There's a difference between the two.
May 10, 2008 7:38:08 PM

stickmans88 said:
I set mine to 120mhz. Is that a bad thing?

It could be. If you don't know what you're doing, lock it to 100MHz. If the vidcard can't handle it, it may burn to death. Also, there may be data corruption by setting it too high.

MSI states on their site that 120MHz is the max. I would stay under 115Mhz, but I did some benchmarks and there was no difference on my 8800GTS 320MB.
May 10, 2008 8:28:07 PM

so there's no differnce in game performance between 100mhz and 120mhz? or even 150mhz? Also why do u guys want to set it at 100mhz? is that the default speed for all the new video cards such as 8800GT, 8800GTS 512mb, 8800GTX and ultra?
May 10, 2008 8:36:11 PM

jincuteguy said:
so there's no differnce in game performance between 100mhz and 120mhz? or even 150mhz? Also why do u guys want to set it at 100mhz? is that the default speed for all the new video cards such as 8800GT, 8800GTS 512mb, 8800GTX and ultra?

I did some tests before. From the default 100MHz, which is what all vidcards are designed to run at, I set it to 115MHz. 3Dmark06 jumped by 10points, after running it 10times and taking the avg of course.

10points increase in 3dmark means nothing in real games, and I did not see any boost. I did find out that OCing improved some by increasing the PCI-E frequency, but the gains were only that, 10points.
May 11, 2008 5:55:48 AM

What will it do for sli/crossfire. Would 100mhz bottle neck the chipset with dual cards?
May 11, 2008 7:02:45 PM

Upping the frequency on the PCI-E bus might help eventually, or with an SLi/Crossfire setup of PCIe 2.0 cards running in PCI-E 1.1 x8 slots, but be certain to stay well clear of 125Mhz, at that speed SATA controllers start acting up.

For a single card setup, you wont see any improvements.
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May 11, 2008 10:30:09 PM

Evilonigiri said:
I did some tests before. From the default 100MHz, which is what all vidcards are designed to run at, I set it to 115MHz. 3Dmark06 jumped by 10points, after running it 10times and taking the avg of course.

10points increase in 3dmark means nothing in real games, and I did not see any boost. I did find out that OCing improved some by increasing the PCI-E frequency, but the gains were only that, 10points.

Here you go (found your testing :)  ):
http://www.tomshardware.com/forum/245190-29-pcie-freque...
May 11, 2008 11:28:41 PM

Oh yeah, haha, thanks Shadow. I was too lazy to look for it. :) 

I'm thinking while this maybe so for my 8800GTS 320MB, it could have better performance gains on, say, a 8800GTS 512MB.
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