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supra
07-06-05, 07:21 AM
elloz,

Been reading about pcie and agp and i have 3 questions.
1. How come theres no agp for 7800?

I read that theres not going to be agp for 7800 but will be for the next series. Is what i read bs, if not why only 7800 wont support agp.

Im not a hardware guru but from what i know pcie is like twice the bandwidth of agp right? But I also read on some website that current games at the moment uses no where near the 8x of agp.

Which bring me to my next question.
2.How close are games to using full capacity of of agp? and how long will that be?

My third question is how come they dont make a agp2 or something? with 16x bandwidth like pcie? Then people can still use their agp cards if they are upgrading motherboards in the future. or is that not possible?

Riptide
07-06-05, 08:25 AM
Well this has already been covered in other threads but yes, PCI Express isn't really needed right now for video cards except in one specific situation (dual / SLI configurations). There are a few other specialized applications where PCI Express comes in handy but they are pretty few. And yes it's true the there is very little performance difference between 4x and 8x AGP at the moment. And it will be that way for a while. Probably years.

They have no reason to make 16x AGP when they can just unify the entire architecture and move us off it entirely - so we have one expansion bus instead of two (PCI + AGP vs. just PCI Express). Make sense?

I won't be getting a PCI Express system until I'm forced into it, and it looks like that's happening sooner than is really needed for us single video card users.

Bluekkis
07-06-05, 08:37 AM
They have no reason to make 16x AGP when they can just unify the entire architecture and move us off it entirely - so we have one expansion bus instead of two (PCI + AGP vs. just PCI Express). Make sense?

To add something to that, PCI-E is also more flexible than old PCI bus. AGP is basically a beefed up dedicated PCI bus for Graphics Card. Also due to paraller nature of AGP/PCI, it isn't as well suited for high speed traffic compared to serial PCI-E.

jolle
07-06-05, 09:43 AM
elloz,

Been reading about pcie and agp and i have 3 questions.
1. How come theres no agp for 7800?

I read that theres not going to be agp for 7800 but will be for the next series. Is what i read bs, if not why only 7800 wont support agp.

I think that NV assumes that the bulk of people who would buy a 7800GTX already is on a high end system with PCI-E.
There isnt no real reason since it draws about the same as 6800U.
Some of the third party manufacturers might put on a HSI bridge and put out a AGP version tho, but there isnt one planned officially from NVidia yet.
They said if there was enough demand they would concider it.


Im not a hardware guru but from what i know pcie is like twice the bandwidth of agp right? But I also read on some website that current games at the moment uses no where near the 8x of agp.

Which bring me to my next question.
2.How close are games to using full capacity of of agp? and how long will that be?

AGP isnt really saturated with gaming.
But PCI-E isnt about that, its replacing the entire PCI subsystem.
On the old PCI subsystem everyhing shared the same 133mb/sec bus, and had to take turns to use it, IDE was also on this bus.
Which is why pretty much everything integrated has been using other highspeed connections like HyperTransport on Nforce mobos and other similar connections, instead of the PCI bus, for years now.

PCI-E 1x is 255mb/sec in both directions at the same time, dedicated per port.
PCI-E 16x is about 4gb/sec bidirectional (8gb total) Full duplex, while AGPx8 is about 2gb up and very slow down (255mb/sec i think).
Thats a good step up, specially in downstream, which is useful with video editing mainly.. but for gaming, its not a issue atm..
Who knows tho, maybe when its mainstream enough they will find a way to use it for something neat..


My third question is how come they dont make a agp2 or something? with 16x bandwidth like pcie? Then people can still use their agp cards if they are upgrading motherboards in the future. or is that not possible?

AGP is part of the old PCI bus, its using a multiplier (the Frontside bus has also been traditionally tied in here, so when you OCed the FSB in the old days without the locks, PCI and AGP could freak out cause it also got OCed).
So without the PCI bus it prolly wouldnt work to make it backwards compatible with AGPx8, could prolly have ended up PCI-E but just called AGP x16 in the end..

supra
07-06-05, 10:59 AM
ahh ok thnx. That cleared things up.

i came across this which was very interesting!

http://www.cdrinfo.com/Sections/News/Details.aspx?NewsId=13974

how cool will that be? no need to worry about compatiblity :D