pci-e slot explanation

[brewston]

Hi guys

I'm not really up to speed with pci-e - what the do the x16, x1 mean ? is it just the length of the connector ? If a PC is advertised with :

Number of PCI Express x1 Slots 1
Number of PCI Express x16 Slots 1

Does that mean I can install 2 x1 cards in there ? Most tuner cards seem to be x1

Thanks

[Spectrum]

It denotes how many pcie lanes the slot has. More lanes means more bandwidth. x16 is used primarily for video, x8 and x4 are used frequently for HDD controllers and scsi interfaces. x1 is for small things like sound/video/ethernet cards. Usually an x16, x8, or x4 slot will allow an x1 card to be used but hat is not always the case. Check with the MB's manual to be sure. You can never go the other way though, i.e. an x16 card will never work in an x1 slot.

[speck55]

Originally Posted by Spectrum

It denotes how many pcie lanes the slot has. More lanes means more bandwidth. x16 is used primarily for video, x8 and x4 are used frequently for HDD controllers and scsi interfaces. x1 is for small things like sound/video/ethernet cards. Usually an x16, x8, or x4 slot will allow an x1 card to be used but hat is not always the case. Check with the MB's manual to be sure. You can never go the other way though, i.e. an x16 card will never work in an x1 slot.

Depends also on your chipset/board - in Nvidia chipsets, in particular, but on other platforms, I've tried sticking x1 cards like tuners or x4 cards like hardware RAID controllers, into the x16 slot, and for some reason, the x16 slot won't fly for anything but a display adapter.

[davephan]

Here's a link with more information: http://en.wikipedia.org/wiki/PCI_Express

Some of the connectors will not be useful if components on the PC board behind the slot block the card from plugging in the slot, so you have to look out for that problem. You can get extender cables so you could still use blocked slots, but you would have to mount the PCIE card somewhere in the chassis away from the slot.

Dave

[brewston]

Thanks guys. I've done more digging and found it has Intel ICH10 chipset. I can't seem to find any card restrictions through searching google

Since I'd be using it as a headless server, I don't need a graphics card in there so it would be nice if it could be used for another tuner in the future.

[Fuzzy]

Originally Posted by Spectrum

You can never go the other way though, i.e. an x16 card will never work in an x1 slot.

That's not entirely accurate either. electrically, an x16 card would still work in an x1, x4, x8, etc slot, just with reduced bandwidth. The only thing preventing it is the physical connection. There are manufacturers that leave the end of the slot open, so a longer connector will fit in it, and they work fine in most cases. I have seen people mod their MB by slicing the end of the pcie-x1 or x4 slots to accept another x8 or x16 card. I myself on my last MB, opened up the end of an x4 slot to add a x8 raid card. Worked great.

[Spectrum]

Originally Posted by Fuzzy

That's not entirely accurate either. electrically, an x16 card would still work in an x1, x4, x8, etc slot, just with reduced bandwidth. The only thing preventing it is the physical connection. There are manufacturers that leave the end of the slot open, so a longer connector will fit in it, and they work fine in most cases. I have seen people mod their MB by slicing the end of the pcie-x1 or x4 slots to accept another x8 or x16 card. I myself on my last MB, opened up the end of an x4 slot to add a x8 raid card. Worked great.

Wow, that begs the question why did the manufacturer design it as an x8 card if it only needs 4 lanes?

Even though I made an incorrect statement I was trying to keep it simple. I have a MB that has an x8 connector but is only wired for x4. It's clearly stated in the manual that this is the case though; Supermicro isn't trying to fool anyone. Maybe storage adapter manufacturers are notorious for designing an x4 card and putting it in an x8 body...

Whatever the reason, thanks for the correction

[Fuzzy]

Originally Posted by Spectrum

Wow, that begs the question why did the manufacturer design it as an x8 card if it only needs 4 lanes?

Even though I made an incorrect statement I was trying to keep it simple. I have a MB that has an x8 connector but is only wired for x4. It's clearly stated in the manual that this is the case though; Supermicro isn't trying to fool anyone. Maybe storage adapter manufacturers are notorious for designing an x4 card and putting it in an x8 body...

Whatever the reason, thanks for the correction

Because it performs better in an x8 slot. USB 3.0 devices will work in a USB 1.1 socket also, just not near as well.