Question about X800 series memory interface

[kemosabe]

Dave's reviews indicate that the X800 parts support not only GDDR3 but DDR/GDDR2 interfaces. Looking for confirmation, since only GDDR3 is mentioned on ATI's spec page.

The reason I ask is that it seems that GDDR3 memory cost is primarily what is holding ATI back from offering a 12-pipe part for $299. From what at least one review suggests, a cheaper DDR1-based X800 Pro would still wipe the floor with the vanilla 6800 at that price point.

 

[AlphaWolf]

well if you check the b3d charts you will see an X800SE part on there with normal ddr ram.

Here.

And the R420 chip lists support for ddr, gddr2, gddr3, here

 

[KimB]

The reason I ask is that it seems that GDDR3 memory cost is primarily what is holding ATI back from offering a 12-pipe part for $299. From what at least one review suggests, a cheaper DDR1-based X800 Pro would still wipe the floor with the vanilla 6800 at that price point.

Why?

 

[AlphaWolf]

The reason I ask is that it seems that GDDR3 memory cost is primarily what is holding ATI back from offering a 12-pipe part for $299. From what at least one review suggests, a cheaper DDR1-based X800 Pro would still wipe the floor with the vanilla 6800 at that price point.

Why?

Perhaps because of the much higher core clock on the X800pro?

 

[kemosabe]

The reason I ask is that it seems that GDDR3 memory cost is primarily what is holding ATI back from offering a 12-pipe part for $299. From what at least one review suggests, a cheaper DDR1-based X800 Pro would still wipe the floor with the vanilla 6800 at that price point.

Why?

Perhaps because of the much higher core clock on the X800pro?

A 150 MHz core clock difference would seem like a sufficient explanation to me too. Looking at Brandon's benchmarks, seems to me ATI would have a winner on their hands even with slightly slower DDR1 memory than the current 450 MHz GDDR3 spec.

 

[KimB]

What would make you think that a lower-cost version would have the same core clock?

 

[jvd]

I dunno the rummors are still pointing at the x800pro dropping to 300$ and a x800xt agp version coming out at 400$

 

[kemosabe]

What would make you think that a lower-cost version would have the same core clock?

For one thing the X800 core has lots of headroom even at 475 MHz, so yields would not likely be problematic, but even with lower clocks the large performance lead over the 6800 wouldn't evaporate. I'd be curious to see a 400/400 12-pipe DDR X800 up against the 6800.

 

[AlphaWolf]

I don't think we will see anything in the way of price drops or new cards from ATi until they are done filling up the OEM market. My bet is August we might see something.

The card they choose to fill that gap will likely depend on yields. If yields are really good there is no reason they couldn't use a 16 pipe part and place it between the pro and the xtpe or a 12 pipe part paired with ddr1 placed below the x800pro.

 

[jvd]

I don't think we will see anything in the way of price drops or new cards from ATi until they are done filling up the OEM market. My bet is August we might see something.

The card they choose to fill that gap will likely depend on yields. If yields are really good there is no reason they couldn't use a 16 pipe part and place it between the pro and the xtpe or a 12 pipe part paired with ddr1 placed below the x800pro.

Its my understanding that yields of 16 pipe parts are very very good much better then they thought.

so a 500mhz 16x1 or even 475x16 may well be very possible and may be a sweet spot in terms of ram .

 

[KimB]

Except that it costs a lot to fabricate each one of those chips. Since this would be a high-volume design, they'd be more likely to fabricate a chip with physically fewer pipelines to fill this section of the market.

 

[jvd]

Except that it costs a lot to fabricate each one of those chips. Since this would be a high-volume design, they'd be more likely to fabricate a chip with physically fewer pipelines to fill this section of the market.

I'm not sure what you mean.

They aren't producing anything but 16 pipeline cards from the x800 series. Its just a certian amount that have 4 pipes disabled .

IF yields are better than they thought they could introduce a new variant at the 400$ price range . Costing the same as the x800pro .

 

[AlphaWolf]

Except that it costs a lot to fabricate each one of those chips. Since this would be a high-volume design, they'd be more likely to fabricate a chip with physically fewer pipelines to fill this section of the market.

If nvidia can do it with a 222 million transistor part I see no reason ati can't do it with 160 million transistor part.

 

[KimB]

1. It's on a different process, which means the cost is different.
2. Apparently ATI doesn't count cache transistors, so they can't be directly compared.

 

[kemosabe]

Except that it costs a lot to fabricate each one of those chips. Since this would be a high-volume design, they'd be more likely to fabricate a chip with physically fewer pipelines to fill this section of the market.

If nvidia can do it with a 222 million transistor part I see no reason ati can't do it with 160 million transistor part.

Precisely. If you're getting strong yields on 3 and 4 quad cores, and you've got an obvious core clock advantage, there's no compelling reason to risk losing the performance battle against a 12-pipe part by crippling a second quad. Of course there might be a certain cost disadvantage vs. the 6800 related to the low-k process. In any case, the 6800 is currently being hailed as the best option at the $299 price point by default, since ATI has no competing R420-based ASIC on the market. A slightly slower 12-pipe DDR part could easily become the next Ti4200.

 

[KimB]

I'm not sure what you mean.

They aren't producing anything but 16 pipeline cards from the x800 series. Its just a certian amount that have 4 pipes disabled .

Right. And if they produced a card that had 12 actual pipelines, it'd be cheaper for them to manufacture.

 

[AlphaWolf]

1. It's on a different process, which means the cost is different.
2. Apparently ATI doesn't count cache transistors, so they can't be directly compared.

This discussion has been had 10000 times and no one has provided any valid evidence of transistor counts, but I think it can be agreed that the 6800 has more transistors. So saying that the r420 can't be sold in a cut down version effectively but the 6800 can is just more Chalnoth FUD.

 

[jvd]

I'm not sure what you mean.

They aren't producing anything but 16 pipeline cards from the x800 series. Its just a certian amount that have 4 pipes disabled .

Right. And if they produced a card that had 12 actual pipelines, it'd be cheaper for them to manufacture.

yet they would have to make a new core . Which would mean tap outs and masks which would cost alot. Don't see why they would do that

 

[Fodder]

If you're getting strong yields on 3 and 4 quad cores, and you've got an obvious core clock advantage, there's no compelling reason to risk losing the performance battle against a 12-pipe part by crippling a second quad.

How about product line segmentation? A $300USD R420 ASIC has to be crippled in some way so it doesn't eat up all the X800Pro sales. Either through disabling a second quad, underclocking & undervolting, or pairing it with insufficient memory bandwidth (either through a 128-bit bus or slow DDR1).

 

[KimB]

It's not a question of can or can't. It's a question of will or will not. ATI may think that they have the $300 market covered just fine, and would rather take higher margins on the X800 parts right now. I don't know.