SG33G5 - PCIEX clock setting

azenz · 08-27-2007, 04:09 PM

I assume the PCIEX clock set in the bios locks the PCIEX speed at that setting independently of FSB speed. Now, does this also affect the PCI bus speed which runs at 1/3 of PCIEX (33 vs. 100 Mhz), or will the PCI bus speed change when FSB speed is altered?

I run SG33G5 with Q6600 (2.4 Ghz)

**SHUTTLE - Eric Wang** · 08-27-2007, 04:45 PM

Hey azenz,

Yes, the PCI-E bus speed is different to the CPU and RAM.
Changing PCI-E bus speed will not affect your PCI bus speed, as they are two separate things.

azenz · 08-27-2007, 05:07 PM

So basically if dynamic overclocking is activated then the PCI express bus speed remains constant but PCI speed increases, right?

In my Shuttle SG33G5, which components are attached via PCIEX and which via PCI? For example, I am using an external USB hard drive. With dynamic overclocking activated, I wonder if the hard drive or any other components are at risk...

**SHUTTLE - Eric Wang** · 08-27-2007, 05:19 PM

With dynamic overclocking, it only affects your CPU and RAM bus speed, PCI-E and PCI bus speeds remain untouched. So if you need to you will need to manually change those on your PCI-E.
The only devices affected by PCI-E or PCI are those that you plug into the slots, USB and other devices are controlled by other components on the motherboard.

azenz · 08-27-2007, 05:27 PM

Ok, just to be absolutely certain, with DoC the speed of writing to USB devices due to FSB increases remains unchanged at any time, and therefore DoC will not pose a risk to an external hard drive, correct?

I am asking because the main issue with overclocking is usually that FSB speed increases will directly affect PCI/AGP/USB systems (as PCI/AGP bus speed increase accordingly) and may cause related devices to fail.

**SHUTTLE - Eric Wang** · 08-27-2007, 05:32 PM

In theory, I think so as I cannot promise you anything :p
I don't see how it could, maybe someone else has a better answer for this.
The main issue I can think of with oveclocking is either your CPU dies or your motherboard dies, don't see why an external USB drive would be affected.

azenz · 08-27-2007, 05:35 PM

Thanks :). I once overclocked a system by 10% and PCI speed was not locked (also increase by 10%) and then loaded 10GB to my external USB drive, and afterwards my drive was no longer recognised. Hard drive failure due to overclocked PCI (if USB runs on PCI) is a common issue (if you google around). I still suspect that on the Shuttle, USB devices will be affected by a higher FSB.