PCI Express Basics, Where Can I Get Info?

[HansGroenewold]

Can someone tell me where I can I get some basic information regarding PCI Express please? My motherboard of one year just died and I just bought a ASROCK 939Dual-SATA2 M1695 939 motherboard since I wasn't ready to part with my AGP 256MB eVGA 6800 Ultra card just yet. This board also has PCI Express capabilities. Don't you have to have two identical cards and a bridge connecting the two for this to work? Any help would be appreciated.

Sincerely,
Hans Groenewold

 

[moonboy403]

i think what you're referring to is sli (in which your board isn't sli capable)

just plug your agp card in and it'd work just fine

or you can upgrade and buy a pcie card

 

[SpeedZealot369]

It should work fine, what your reffering too is SLi, and thats different.

 

[HansGroenewold]

So what's the advantage of PCI Express? Is it because the PCI slot processes more data that a AGP slot? I'm assuming that SLI is the one where you have two video cards joined by a bridge?

Thanks,
Hans

 

[moonboy403]

sli is what you mentioned

pcie really doesn't have any real world advantage yet
the only theoretical advantage that pcie has is its large bandwidth, but the extra bandwidth is useless rigtht now

btw...pcie is cheaper than agp

 

[HansGroenewold]

PCI video cards are cheaper? Why would the bandwidth be useless right now?

Thanks,
Hans

 

[moonboy403]

it's useless because we're not bottlenecked by bandwidth

 

[SpeedZealot369]

Originally posted by: moonboy403
it's useless because we're not bottlenecked by bandwidth

Yepp, but sli wouldnt be possible with agp though.

 

[MDE]

Originally posted by: SpeedZealot369

Originally posted by: moonboy403
it's useless because we're not bottlenecked by bandwidth

Yepp, but sli wouldnt be possible with agp though.

Actually, the AGP 8x spec allows for two slots. It just wasn't implemented.

 

[HansGroenewold]

PCI Express must have had a benefit to justify going to it. I read an article on it on the Microsoft web site and the rationale behind it made sense.

Sincerely,
Hans

 

[Peter]

There are many benefits in PCIE ... it's electrically much more robust than AGP, there are no technical constraints on slot count since it's all point-to-point not a bus, board layout is easier, the PCIE-16 slot provides more power to the graphics card than AGP did, lesser PCIE slot types use much less real estate than PCI slots did, and probably tons more.

 

[Golgatha]

Originally posted by: Peter
There are many benefits in PCIE ... it's electrically much more robust than AGP, there are no technical constraints on slot count since it's all point-to-point not a bus, board layout is easier, the PCIE-16 slot provides more power to the graphics card than AGP did, lesser PCIE slot types use much less real estate than PCI slots did, and probably tons more.

I think most of the draw was to move away from PCI more than AGP (which is a similar spec to PCI I believe) for the added dedicated bandwidth the PCIe slots provide. It gives motherboard makers a way to simplify their designs and make designs for the server and workstation market more similar, thus reducing costs.

 

[Peter]

That's the other angle of conversion. PCIE brings the graphics card slot(s) back from being "special" into using the same technology as all other slots - the way it used to be in PCI and ISA days.

Also, desktop boards get their PCI bandwidth problems resolved with the migration to PCIE-1x slots. (This is a problem server/workstation boards never had - multiple busses and faster slot specifications like PCI-X have been common there.)

 

[Matthias99]

Originally posted by: Golgatha

Originally posted by: Peter
There are many benefits in PCIE ... it's electrically much more robust than AGP, there are no technical constraints on slot count since it's all point-to-point not a bus, board layout is easier, the PCIE-16 slot provides more power to the graphics card than AGP did, lesser PCIE slot types use much less real estate than PCI slots did, and probably tons more.

I think most of the draw was to move away from PCI more than AGP (which is a similar spec to PCI I believe) for the added dedicated bandwidth the PCIe slots provide. It gives motherboard makers a way to simplify their designs and make designs for the server and workstation market more similar, thus reducing costs.

The laptop market, too.

PCIe is faster, but not dramatically faster, in 'downstream' (ie, PC->graphics card) bandwidth. However, PCIe has WAY more 'upstream' (graphics card->PC) bandwidth. This is pretty irrelevant right now, but could become important for things like doing video encoding on your GPU, or when "AIW"-type cards start coming with HDTV tuners built in.

Beyond that, it's basically all the stuff mentioned above: It's cheaper/easier to manufacture on MB and graphics card side, since it doesn't need nearly as many traces, it provides more power, it's MUCH easier to have multiple high-speed PCIe devices, it's not a shared bus like PCI or AGP, and -- at some point, in theory -- every expansion device in the entire system can use one kind of slot/interface (just about anything short of a GPU or RAID controller can use a PCIex1 interface just fine). That would be a really nice thing to have from a system integrator's perspective.