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Quote:


Originally Posted by Mastacator

Anyone overclocking the PCIe bus?
Benefits/risks?
What your PCIe bus overclocked at if it is?

I'd leave this as 100Mhz. Raising it much higher can cause problems without any benefit
 

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I've tried raising mine to 105 (cuz somebody said that was a good speed for ATI cards). Anyways it caused nothing but problems, I didn't run any benchmarks to see if it helped performance wise, because I was too busy with blue screens and random reboots.

 

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Up to 110MHz is a good speed for ATi's and up to 105MHz for nVidia's. Some boards may limit your overclockability with the PCI-E bus locked in to 100.
 

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Discussion Starter #5
Interesting points so far. Mine is running terrific at 113mhz. Seen a 650 point jump in 3Dmark05 with it also.
 

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Quote:


Originally Posted by Chim3ra

Up to 110MHz is a good speed for ATi's and up to 105MHz for nVidia's. Some boards may limit your overclockability with the PCI-E bus locked in to 100.


How does it limit the overclockability of some boards?
 

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Try booting at a lower PCI-E bus, it really isn't recommended to run it so high, as it may lead to instability and data corruption. I however have it up around the same frequency without any problems. If you can get it to run at a lower speed, I recommend that you do so.

One sign of a mismatch between PCI-E and FSB is that when you boot, you will have no video however all your other components will power up and it will sound as if it is POSTing. If you get no video just power off the rig and restart and raise the FSB 1 MHz.

Quote:


Originally Posted by YeaBaby

How does it limit the overclockability of some boards?


Before I figured out that I had to leave my PCI-E bus unlocked while I overclocked I was stuck at 218MHz with no video shown past that speed. Once I upped the PCI-E bus my video came back. I don't know if this is an inherent thing with an ABit/ATi combo but it has happened to a couple of other members.
 

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Discussion Starter #8
Quote:


Originally Posted by Chim3ra

Try booting at a lower PCI-E bus, it really isn't recommended to run it so high, as it may lead to instability and data corruption. I however have it up around the same frequency without any problems. If you can get it to run at a lower speed, I recommend that you do so.

One sign of a mismatch between PCI-E and FSB is that when you boot, you will have no video however all your other components will power up and it will sound as if it is POSTing. If you get no video just power off the rig and restart and raise the FSB 1 MHz.

Really? I haven't had any problems at all! GPU's idle temp is higher with it, but nothing to be alarmed about. Load temps still the same either way. nTune clocked it up to 114, I set it one lower for an extra buffer.
 

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I have overclocked my PCI Express bus to 145 MHz (the top my motherboard supports) without any issues. No stability problems here.


Overclocking the PCI Express bus generally does not do much in terms of performance. The benefits of the higher speed only show themselves when the PCI Express bus is the bottleneck, which is rare. This is why overclocking PCI-E does not produce the same performance boost that raising the AGP bus does. It's also possible to get data corruption (blah blah blah, the usual stuff non overclockers say) since the peripherals are not designed to run that fast but again I haven't experienced any problems.
 

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To Chimra

Alright I'd assume it was a board by board thing. I've had my DFI up to 317 Mhz. with the PCIe locked with no problems. Ran a big ram divider and a low cpu multi though. I had a Soltek board and if I changed the PCIe bus bad things would happen. (see previous post) LOL.
 

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Discussion Starter #11
Quote:


Originally Posted by OC Newbie

I have overclocked my PCI Express bus to 145 MHz (the top my motherboard supports) without any issues. No stability problems here.


Nice!!

Quote:


Originally Posted by OC Newbie

Overclocking the PCI Express bus generally does not do much in terms of performance...

Really? I did see a jump in my 3Dmark05 score though. I must have a bottleneck of sorts.
 

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Quote:


Originally Posted by Mastacator

Really? I did see a jump in my 3Dmark05 score though. I must have a bottleneck of sorts.

With an increased PCI Express bus, data can move between the devices and the Northbridge faster. Since you're running SLI, it's possible that the 6600GT's individually need more bandwidth than PCI Express x8 natively supports, thus when you increase the speed of your PCI Express bus, you're increasing the amount of bandwidth available to the videocards.

I'm running SLI as well so I guess I should have noticed a similar performance boost but then again I did not test very long. I'll try it out (not tonight though, it's my wedding anniversary
) and let you know my results later.
 

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Discussion Starter #13
Quote:


Originally Posted by OC Newbie

With an increased PCI Express bus, data can move between the devices and the Northbridge faster. Since you're running SLI, it's possible that the 6600GT's individually need more bandwidth than PCI Express x8 natively supports, thus when you increase the speed of your PCI Express bus, you're increasing the amount of bandwidth available to the videocards.

I'm running SLI as well so I guess I should have noticed a similar performance boost but then again I did not test very long. I'll try it out (not tonight though, it's my wedding anniversary
) and let you know my results later.


That is what I was thinking exactly. Since SLI lowers the bandwith per card to x8, I started to think that raising the PCIe bus would help that out. Didn't mess with it when i was running single card.

HA!! Yeah, i wouldn't mess with it tonight either if i were you. Got some other overclocking to do, Hee, Hee, Heehee!
 

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Discussion Starter #15
Quote:


Originally Posted by MADMAX22

so does this just affect your video cards or will it affect say your sound card also, another thing you guys say data coruption so does it your hdd's as well or just your northbridge

thanks for any more info

I'm not sure what else runs on the PCIe bus, besides graphics. I don't know for AMD. Seems i remember reading that on some Intel i9** chipsets the FSb is some how interconnected to the PCIe, so overclocking anything doesn't work well. I tend to think a sound card would be on the standard PCI though.
 
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