AGP speeds

[Molondo]

What do the speeds mean? An increase of frequencies? Better ram?
Thanks 🙂

 

[Bobthelost]

Not much in real terms.

Now if you'd asked about PCIe then it's a matter of bandwidth.

 

[mwmorph]

bandwith. Agp 1x, 2x, 4x, 8x just mean how many times a cycle it will signal(change voltage ). AGP 2x would carry 1 signal(change in electrical charge) per cycle. AGP2x woud do it once on the up part of the cycle and once when the cycle fell back down, AGP4x would do it twice on the upside and twice on the downside, etc up to agp8x.
a signal looks like this
/\_/\_/\_/\_/\_/\_/\_/\_/\_/
now agp just has tiny blips as the voltage raises and lowers to indicate a signal.

 

[BFG10K]

FYI - x16 is only for PCIe while x8 is both for PCIe and AGP.

The numbers refer to available bandwidth.

 

[xtknight]

PCIe x8 is faster than AGP 8x, right?

 

[Kroz]

I thought PCIe for graphcs is x16?

 

[TheRyuu]

Originally posted by: Kroz
I thought PCIe for graphcs is x16?

It is, but it can also be x8 too. Like on most SLI mobo's when you put it in SLI it makes both slots x8 because it doesn't have enough PCIe lanes.

 

[BFG10K]

PCIe x8 is faster than AGP 8x, right?

Both are around 2 GB/sec but PCI express can do it bi-directionally for a total of 4 GB/sec.

 

[dguy6789]

Originally posted by: BFG10K

PCIe x8 is faster than AGP 8x, right?

Both are around 2 GB/sec but PCI express can do it bi-directionally for a total of 4 GB/sec.

Correct.

AGP can only do data in one direction at a time.
1x= 250MB\s
2x = 500MB\s
4x = 1GB\s
8x = 2GB\s

PCIe x16 is bidirectional 4GB/s.

 

[McChokolat]

i have a mobo with a x8 slot and no x16, is there any video card that i can use for this thing?

there is no agp slot either, so i cant put my x800 in there, and the onboard video card is pretty crummy.

 

[Creig]

AGP 1x = 266 MB/s
AGP 2x = 533 MB/s
AGP 4x = 1066 MB/s
AGP 8x = 2133 MB/s

PCI, 32-bit, 33 MHz = 133 MB/s
PCI, 32-bit, 66 MHz = 266 MB/s
PCI, 64-bit, 66 MHz = 532 MB/s

PCIe x1 = 250 MB/s
PCIe x4 = 1000 MB/s
PCIe x8 = 2000 MB/s
PCIe x16 = 4000 MB/s

 

[Creig]

Originally posted by: McChokolat
i have a mobo with a pcie x8 slot and no agp slot.
can i put a x16 graphics card in the x8 slot?

No. PCIe will allow you to install a lower multiplier card into a higher multiplier slot (ie 1x card in an 8x slot), but you can't go the other way (ie 16x card into an 8x slot).

 

[Alaa]

why dont we see for example PCIex4 instead of PCI in motherboards?

 

[McChokolat]

is there any video card at all that i can use?
everything i've looked at says pciex16...

 

[Golgatha]

Originally posted by: Creig

Originally posted by: McChokolat
i have a mobo with a pcie x8 slot and no agp slot.
can i put a x16 graphics card in the x8 slot?

No. PCIe will allow you to install a lower multiplier card into a higher multiplier slot (ie 1x card in an 8x slot), but you can't go the other way (ie 16x card into an 8x slot).

Some people have had success cutting away the plastic on an 8x card slot (cheap Dell deal servers mainly) and running 16x video cards in 8x mode. However, this is obviously not a supported way of making it work.

http://www.tkdan.com/SC420/

 

[McChokolat]

seems weird to cut out the slot with half the pins hanging out...

 

[McChokolat]

what about the pins that belong where the divider is on the slot? when you cut the plastic out, there are no pins on the slot, yet there are contacts on the corresponding spot on the video card itself.

 

[CKTurbo128]

Hmm, I recall way back when Tom's Hardware (I think?) wrote an article about differences in speed on PCI-E. In that article, they used a PCI-E GeForce 6800 Ultra and ran it at PCI-E x1, x4, x8, x16 speeds; I think they taped the connectors to get it running in a slower slot. I can't find that article though.

 

[McChokolat]

i've heard people doing this too, but i honestly dont see why there would be so many pins on the card, yet it works on different side pcie slots

 

[ElFenix]

Originally posted by: McChokolat
i've heard people doing this too, but i honestly dont see why there would be so many pins on the card, yet it works on different side pcie slots

the card just communicates over the lanes it has access to, i guess.

just like how early sli chipsets went to x8 when two cards were put in. the card obviously has to run on 8 lanes then.

 

[Fox5]

Originally posted by: dguy6789

Originally posted by: BFG10K

PCIe x8 is faster than AGP 8x, right?

Both are around 2 GB/sec but PCI express can do it bi-directionally for a total of 4 GB/sec.

Correct.

AGP can only do data in one direction at a time.
1x= 250MB\s
2x = 500MB\s
4x = 1GB\s
8x = 2GB\s

PCIe x16 is bidirectional 4GB/s.

I'm pretty sure AGP can't swap directions, it's 2GB/s one way, 266MB/s the other. (I think 2GB/s read speeds and 266MB/s write speeds)