7800 series on AGP?!

Ultimate Dev'r · Join us on #cemetech-vaporware (Posts: 7297)

I know it's not a good card, but I just don't see why they would go out of their way to make one...after all, the AGP bus can't handle it.

Kllrnohj · ☢ PH34R |\/|3 (Posts: 8196)

thats not true. The AGP bus CAN handle it. Infact, the AGP 8x is NOT saturated with current gen cards. AGP is quite capable in terms of speed, but was rushed out because it is inconvinient (a radeon 9700PRO will get only 1-2 FPS lower w/ AGP 4x vs. 8x). AGP required its own bus seperate from PCI - PCI-E uses the same bus, reducing chip complexity and other such problems

Also, when running SLi on non-nForce4 SLI X16, one of the x16 slots runs at x8 speeds because the nforce4 SLI doesn't have enough lanes. PCI-E x8 is the EXACT same speed as AGP 8x - yet no one was claiming that the x8 slow was hurting performance Wink

If nvidia wanted to, they could make the 7800GTX WITHOUT any GPU changes be an AGP card, but there just isn't a market for that sort of thing, as anyone who's going to drop $600 for a video card probably has PCI-E Laughing

Kllrnohj · ☢ PH34R |\/|3 (Posts: 8196)

let me re-explain this

1x7800GTX @ x16speeds = 2xAGP 8x

2x7800GTX in SLi == 1@x16, 1@x8 == 1@2xAGP 8x, 1@AGP 8x

So one of the 7800GTXs when in SLi will run at x8 PCI-E speed, which is the same as AGP 8x. Therefore it would be perfectly possible to run 1 7800GTX at x8 speeds just fine, which therefore means it could run on an AGP slot just fine

This is not just a theory, it can be verified. Compare SLi graphics speeds in a nForce 4 SLi and an nForce4 SLi X16. On the later both cards run at full x16 speeds, yet there is very little, if any, performance increase...

Ultimate Dev'r · Join us on #cemetech-vaporware (Posts: 7297)

Yes, but you lose performance, which is what I was saying Wink

Kllrnohj · ☢ PH34R |\/|3 (Posts: 8196)

Yes, but you lose performance, which is what I was saying Wink

Kllrnohj · ☢ PH34R |\/|3 (Posts: 8196)

an nForce 4 SLI chipset CANNOT handle 2 x16 PCIe slots (it doesn't have enough PCIe lanes), hence, when running in sli mode one is x16, the other is x8, as that is all the lanes the chipset can handle. (or for early SLi boards, both are x Cool

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When playing a game, bandwidth is NOT important between the card and the mobo. The reason is simple, a vast majority (if not all) of the level data is loaded into the card BEFORE the game starts, not DURING. Hence, only small amounts of data are transfered back and forth during the game, usually just what doesn't fit in the cards framebuffer.

I think you linked to the wrong review, there isn't an AGP card listed - and never link me to tomshardware again - it is the WORST site for computer info EVER

You can do an experiment to see just how important bandwidth really is yourself. Simply force-lower the AGP level in the BIOS. eg: switch from AGP 8x to 4x

Ultimate Dev'r · Join us on #cemetech-vaporware (Posts: 7297)

But that's assuming that the programmers will code a certain way; I'm going by bare-bones raw speed and computing power here, like with 3DMax benchmarks and other GPU-intensive tasks where it pays to have more bandwidth.

Kllrnohj · ☢ PH34R |\/|3 (Posts: 8196)

But that's assuming that the programmers will code a certain way; I'm going by bare-bones raw speed and computing power here, like with 3DMax benchmarks and other GPU-intensive tasks where it pays to have more bandwidth.

Kllrnohj · ☢ PH34R |\/|3 (Posts: 8196)

thats a simple one - because x16 is that of the physical connector Wink

(future proofing is a goal of PCIe)

Kllrnohj · ☢ PH34R |\/|3 (Posts: 8196)

all x16 cards are technically x16 only, as it is really a slot description.

they switch to x8 SPEEDS when in SLi

x8 does work in an x16 slot, just like an x1 will work in an x16 - its upwards compatible, but not downwards