Are Cell Yields Really Doom and Gloom?
Chris sent in this link about the yields on Cell processors being really low. I’ve seen several other articles on the net about the same thing, but decided to hold off on posting about it until I got a second view.
And here it is, from The Register. Yields of 10% to 20% aren’t very good. Sure, I’ll take that. It’ll make the Cell processor more expensive for Sony until they can increase the yields. Sure, I’ll believe that too. But the real problem for me is this: will it mean that Sony won’t be able to ship the PS3’s it promised? Not necessarily. The Register points out that yields of chips with 7 SPE cores operational are 10 to 20 percent. Cell chips with fewer than 7 SPE cores operational can still be used, even if they contain just one usable core. Personally I don’t know who uses these chips but my guess is that IBM would charge less for these chips and that customers would be found. But anyway – that’s getting off topic. We care about the chips with at least 7 operational SPE’s. With yields of 10 to 20 percent, will I still get my PS3? The Register did some napkin math to get the answer “yes”:
At 20 per cent yield, that’s 64 Cells per wafer, so Sony needs 93,7500 wafers to in 4.5 month to get enough Cells. That’s 20,833 wafer starts per month, which isn’t entirely out of order, given not only IBM but Sony will be producing Cells destined for PS3s.
So Sony might just squeek by. Of course, this calculation assumes that yields are 20% and we all know that they’re actually between 10 and 20. But who’s to say that yields won’t increase as time goes by? Actually, we know they will – that’s how these kinds of things work. The question is just how fast will yields increase?
So is it time to panic? No. Is it time to be concerned? Personally, I go by the motto “don’t sweat the little stuff”. So I’m not gonna worry about it. If it turns out to be a problem, then so be it. We’ll complain when the time comes.