Hello everyone,

I recently upgraded my system and I'm curious as to how the PCI Express bus speed affects a PCI-E card's performance? I'm assuming that it increases the bandwidth, but is there a way to determine the new bandwidth based on the MHz of the PCI-E speed?

So, for example, if in the BIOS the PCI bus speed reads as 100 MHz, and a PCI-E x16 slot runs at 4 GB/s (250 x 16), then what does a 10 MHz increase do?

Do I have this wrong or right? Does anyone have some more info on this?

Just curious really, because I understand the FSB x multiplier equation for CPUs, but I'm not understanding what it means for PCI-E cards...

Thanks in advance for all your help,
David

I'd kinda like 2 know also.

Well, since it doesn't appear as though anyone on these forums knows the answer to my question off hand I'm going to try to work through it a little based on my crude knowledge of PCI express cards:

It doesn't appear as though PCI-E cards have a fixed bus width (as one site says, it is not a PCI-E bus), but rather their signaling timing is at 2.5 Gbaud/s as it is a serial connection. This translates into 2.5 GHz/s in terms of the "timing bandwidth". However, since it takes 10 bits to transmit data instead of 8 bits, that figues is divided by 10 instead of eight to arrive at the standard 250 MB/s worth of data transmitted per lane.

That's just a basic summary of PCI express, as most people probably know already. My new question is, is it possible that bumping the clock connection speed from 100 MHz to 110 MHz (for example) is, in effect, bumping the speed from 25 x 100 = 2500 MHz to 25 x 110 = 2750 MHz? Thus, if you had a x16 motherboard, this would increase your bandwidth by a whopping 400 MB/s. In otherwords, is the "multiplier" for PCI express in terms of the MHz on the motherboard actually 25?

Any thoughts on this? As one can probably tell, I'm really curious as to how this works, because it doesn't make sense like AGP cards and processors do.

David