_. SLM ._
27-06-2005, 14:06
Interessante chiave lettura quella di Dave Baumann di Beyond3D:
LINK (http://www.beyond3d.com/forum/viewtopic.php?t=24313&postdays=0&postorder=asc&start=0&sid=764dfeab687afe29ac345b8873706820)
e qui l'estratto di Dave Baumann:
"With G70 now fully dissected we know have a little greater understanding of the part. Of course one element that characterises G70 is that of die size: its big.
Estimates of the die size put it in the order of around 330mm2, which on a 12" wafer would give in the order of around 150-170 full die to the wafer. Now, the issues here are one of yield - the fewer die there are on a wafer the more likely they are prone to defects. An analyst has suggested to us that there may be as many as 130-160 defects per wafer for earlier 110nm lines from TSMC (although the process is now more mature so that is likely to have decreased) which could give could potentially give very low yields for the chips should everyone need to work without any defects at all.
Now, one thing that we have been used to over the past few years releases is that of utilising defect cores in as lower performance products. The pixel pipelines, followed by the vertex pipelines, are taking the majority of the die space on products such as these and so a natural process defect is most likely to manifest itself in one of these areas; by disabling the pixel quad or vertex shader the defect has manifested itself in the IHV is then still able to recoup much of the cost of that particular piece of silicon, rather than wasting the entire die area.
The difference with G70 is that it is even larger than previous die sizes, which means that it is quite possible that full product yields may be quite small. Could it be that, in order to alleviate this, the defect rate is already built in to the current GeForce 7800 GTX and 24 fragment shaders is not the full number that G70 supports? Whilst many have speculated on an Ultra variant still to come and have been looking at the overclocks of the GTX’s to speculate where it may hit, perhaps it could be the case that there are 32 fragment pipelines in G70 and the fully working die are quietly being collected for use at a later date?"
LINK (http://www.beyond3d.com/forum/viewtopic.php?t=24313&postdays=0&postorder=asc&start=0&sid=764dfeab687afe29ac345b8873706820)
e qui l'estratto di Dave Baumann:
"With G70 now fully dissected we know have a little greater understanding of the part. Of course one element that characterises G70 is that of die size: its big.
Estimates of the die size put it in the order of around 330mm2, which on a 12" wafer would give in the order of around 150-170 full die to the wafer. Now, the issues here are one of yield - the fewer die there are on a wafer the more likely they are prone to defects. An analyst has suggested to us that there may be as many as 130-160 defects per wafer for earlier 110nm lines from TSMC (although the process is now more mature so that is likely to have decreased) which could give could potentially give very low yields for the chips should everyone need to work without any defects at all.
Now, one thing that we have been used to over the past few years releases is that of utilising defect cores in as lower performance products. The pixel pipelines, followed by the vertex pipelines, are taking the majority of the die space on products such as these and so a natural process defect is most likely to manifest itself in one of these areas; by disabling the pixel quad or vertex shader the defect has manifested itself in the IHV is then still able to recoup much of the cost of that particular piece of silicon, rather than wasting the entire die area.
The difference with G70 is that it is even larger than previous die sizes, which means that it is quite possible that full product yields may be quite small. Could it be that, in order to alleviate this, the defect rate is already built in to the current GeForce 7800 GTX and 24 fragment shaders is not the full number that G70 supports? Whilst many have speculated on an Ultra variant still to come and have been looking at the overclocks of the GTX’s to speculate where it may hit, perhaps it could be the case that there are 32 fragment pipelines in G70 and the fully working die are quietly being collected for use at a later date?"