The RV870 Story: AMD Showing up to the Fight
by Anand Lal Shimpi on February 14, 2010 12:00 AM EST- Posted in
- GPUs
The Cost of Jumping to 40nm
This part of the story could almost stand on its own, but it directly impacts much of what happened with Cypress and the entire Evergreen stack that it’s worth talking about here.
By now you’ve most likely heard about issues with TSMC’s 40nm process. While the word is that the issues are finally over, poor yields and a slower than expected ramp lead to Cypress shortages last year and contributed to NVIDIA’s Fermi/GF100 delay. For the next couple of pages I want to talk about the move to 40nm and why it’s been so difficult.
The biggest issue with being a fabless semiconductor is that you have one more vendor to deal with when you’re trying to get out a new product. On top of dealing with memory companies, component manufacturers and folks who have IP you need, you also have to deal with a third party that’s going to actually make your chip. To make matters worse, every year or so, your foundry partner comes to you with a brand new process to use.
The pitch always goes the same way. This new process is usually a lot smaller, can run faster and uses less power. As with any company whose job it is to sell something, your foundry partner wants you to buy its latest and greatest as soon as possible. And as is usually the case in the PC industry, they want you to buy it before it's actually ready.
But have no fear. What normally happens is your foundry company will come to you with a list of design rules and hints. If you follow all of the guidelines, the foundry will guarantee that they can produce your chip and that it will work. In other words, do what we tell you to do, and your chip will yield.
Global Foundries' 2010 - 2011 Manufacturing Roadmap
The problem is that if you follow every last one of these design rules and hints your chip won’t be any faster than it was on the older manufacturing process. Your yield will be about the same but your cost will be higher since you’ll bloat your design taking into account these “hints”.
Generally between process nodes the size of the wafer doesn’t change. We were at 200mm wafers for a while and now modern fabs use 300mm wafers. The transistor size does shrink however, so in theory you could fit more die on a wafer with each process shrink.
The problem is with any new process, the cost per wafer goes up. It’s a new process, most likely more complex, and thus the wafer cost is higher. If the wafer costs are 50% higher, then you need to fit at least 50% more die on each wafer in order to break even with your costs on the old process. In reality you actually need to fit more than 50% die per wafer on the new process because yields usually suck at the start. But if you follow the foundry’s guidelines to guarantee yield, you won’t even be close to breaking even.
The end result is you get zero benefit from moving to the new process. That’s not an option for anyone looking to actually use Moore’s Law to their advantage. Definitely not for a GPU company.
The solution is to have some very smart people in your company that can take these design rules and hints the foundry provides, and figure out which ones can be ignored, and ways to work around the others. This is an area where ATI and NVIDIA differ greatly.
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wlee15 - Sunday, February 14, 2010 - link
The USS Hornet is a carrier not a battleship.For shame Anand For Shame!
Anand Lal Shimpi - Monday, February 15, 2010 - link
wow - you're totally right, I can't believe I made that mistake. Looks like Ryan or Jarred caught it shortly after it went live though, whew :)And yes, for the record, I know the difference between an aircraft carrier and a battleship :)
Take care,
Anand
just4U - Tuesday, February 16, 2010 - link
LIES!!!!(hah)
Sahrin - Sunday, February 14, 2010 - link
Thank you - I was worried I'd be the only one to point this one out.Thank you Anand! This stuff is incredible. Just a few weeks ago I was looking back on the RV770 article and wishing it could be done again.
Kudos as well are due to AMD's PR guys - for having the courage to let the engineers sit down with the press, instead of needing to be there as minders. I guarantee you that every single time, the same story told by a marketer of a product and by the guy whose passion created the product will be a thousand times more effectively conveyed by the engineer. Marketers have value - I'm not trying to write them off.
I don't know what I can do for AT and AMD to thank them for making articles like this happen. Aside from buying Cypress and being a reader - but if there is anything we can do to ensure these articles keep coming (bombard Meyer with Faxes?) let me be the first to sign up. (And maybe if we could get access to AMD's CPU guys as well, to provide a balance to the excellent information we get from Intel).
Dianoda - Sunday, February 14, 2010 - link
This article was a real treat, keep 'em coming...dzx - Monday, February 22, 2010 - link
I created an account just to give thanks for such a well written, informative article. I can sense you have just as much passion for the technology as the engineers and architects who create it. Simply a pleasure to read.gralex - Friday, February 26, 2010 - link
Thanx. I have nothing more to add that hasn't been said already in the above comments, just thanks.As for ATI vs. NVIDIA, maybe i'm believing the hype but AMD seems awfully conservative at the moment. It's totally working for them, of course, but I'm liking the whole CUDA, Tegra2, Ion, Optimus momentum Nvidia might finally be gaining right now. Obviously they messed it up with a ton of rebranding making a 5xxx purchase a no-brainer right now... I just LOVE the way Nvidia was looking cornered and thought up a number of ways to get out. I hope these two keep up the healthy rivalry for many years to come, for ALL of us:-)
phaxmohdem - Sunday, February 14, 2010 - link
Wow. This was perhaps the first article I've read in a long time I read cover-to-cover, and couldn't put down. AT is my favorite tech review site, but I find myself reading the first two pages or so, skipping around to various benchmark pages, then reading the summary. This piece was remarkably intriguing and thought provoking. I look forward to the RV970 story, or perhaps better yet, the GF100 story.Keep em coming!
gimmeausername - Sunday, February 14, 2010 - link
Did you just say RV970?I think you've just made some folks at AMD flip out by using that code name. :D
coolhardware - Sunday, February 14, 2010 - link
As others have mentioned, articles like this one really put Anandtech head and shoulders above the competition. It is so very interesting to find out the real world story behind the video cards. What a wonderful Valentine's Day treat :-).Thanks for all your hard work Anand, I really appreciate it!