PCI Express Frequency and OCing

[9mmx19]

I know that default its 100 but Ive had it on "Auto" on my P5B. Ive read that that means the board will scale it up according to your FSB. Since Im OCing a E6300 the FSB can get a lot higher that stock. So should I be setting this manually to "100"? Similarly should I be setting the PCI bus to 33?

Thanks in advance.

 

[Endurancevm]

If you really want to touch it manually, you can set it to 101 and make sure it stays locked by using clockgen to OC on your desktop, or any other way you see fit. Clockgen is just easier for some.

 

[Domini]

i recommend leaving it on 100 theres really no change at all unless you want to take a risk but i heard 115mhz is the sweet spot for ocing but i wouldnt recommend doing it. also i could be wrong on the speed.

 

[9mmx19]

I like clockgen too but support for the P5B Vanilla isnt out yet =(

And by "OCing" I only meant CPU/RAM not the video card itself so "100" is fine right?

 

[Domini]

yes leave it at 100 for the pci-e clock. you are able to change the cpu fsb as you want. it will effect ram speed, but it a good way.

 

[StealthyFish]

yeah, i'd be careful. I've heard things like, high PCIe frequencies result in hard drive damage and stuff. I just lost my 160Gb hard drive with some organization problem. I'm guessing my PCIe frequency might have been the culprit. You can take the risk, but know there's a chance you can damage your hard drive.

 

[jmphx]

yeah, i'd be careful. I've heard things like, high PCIe frequencies result in hard drive damage and stuff. I just lost my 160Gb hard drive with some organization problem. I'm guessing my PCIe frequency might have been the culprit. You can take the risk, but know there's a chance you can damage your hard drive.

I've only heard of this corruption issue in regards to the PCI bus and not PCI-E. In this case, you need to lock your PCI bus to 33mhz.

I have been running my pci-e clock at 110mhz since I built my new rig (march'06. s939, 3800 x2, Asus A8N-E mobo, 7900 GT voltmodded).

I read somewhere that 110mhz was the 'sweet spot' if OC'ing the pci-e bus. I haven't tried any other speeds, and the box has been solid at 110mhz for many months now.

 

[legendz411]

What exactly does the PCI-E Bus affect? I thought it was only the PCI=E card locked in there, why would it affect anything else?

Pelase explain.

 

[Arcygenical]

Yeah, it affects the speed that the PCIe bus can access the CPU and RAM resources. A PCIe 16x slot (your GPU slot) can transfer at 4gbps full-duplex (ie, up and down per second) when clocked at 100mhz. Nothing can saturate that bus. The only reason I'd think to bring it over 100 is when you have like, 2 gpus and a high performance RAID card/tv Card... Even then...

I've only heard of this corruption issue in regards to the PCI bus and not PCI-E. In this case, you need to lock your PCI bus to 33mhz.

Me too. I've heard of cards burning out above their PCIe 100mhz standpoint... But the SATA bus often runs off the PCIe clock too

Any good performance gains at 110?

**EDIT** supposedly Nvidia is planning on implimenting a "22x PCie" bus in their 590 chpset deemed: Trinity. I wonder how this will affect things.

 

[jmphx]

Me too. I've heard of cards burning out above their PCIe 100mhz standpoint... But the SATA bus often runs off the PCIe clock too

Ah, good point. I didn't consider that.

Any good performance gains at 110?

Don't know actually. I've been literally running at 110 since just a few days after putting this rig together, so I don't have before/after benchmarks, but I'll run some when I get some free time.

*edit: Ok, I did some quick benchmarks w/ 3Dmark06. The score difference between 100 and 110mhz on the pcie clock was less than 10 points lower on 100. I would call this insignifcant. I'll probably be stickin to 100