The RV870 Story: AMD Showing up to the Fight
by Anand Lal Shimpi on February 14, 2010 12:00 AM EST- Posted in
- GPUs
Carrell Loses His Baby: Say Goodbye to Sideport
Sitting at dinner with Eric Demers and Carrell Killebrew is honestly one of the best experiences I’ve ever had working with ATI. Before he got huge and subsequently left, I used to have annual dinners with Pat Gelsinger at Intel. They were amazing. To get to sit at the same table as someone as talented and passionate as a Gelsinger, Demers or Killebrew is one of the most fortunate and cherished parts of my job.
Eric was telling me about how they trimmed down 870 from over 400mm2 down to 334mm2 and how wonderful the end product was. I stopped him and asked for more detail here. I wanted an example of a feature that they had to throw out but they really wanted to keep in. Manufacturers rarely tell you what they threw out, marketing likes to focus on what’s in the chip and make everything sound like a well calculated move. Thankfully, marketing wasn’t allowed to speak at my dinner.
Eric turned to Carrell and said: “i know one feature we could talk about.”
“Sideport”.
Carrell responded, “OH MY GOD, that’s totally not fair.” (note that Carrell does not sound like a teenage girl, imagine that phrase just spoken more engineer-y).
When ATI first talked about the Radeon HD 4870 X2 they told us about a feature called Sideport. It was a port off each RV770 GPU that could be used for GPU-to-GPU communication.
Sideport as it was intended to be used
The whole point of doing CrossFire in alternate frame rendering mode (AFR) is that the chips never have to talk. The minute you have to start synchronizing them, you kill performance. Sideport was supposed to alleviate that.
Unfortunately, due to power reasons, Sideport was never used on the 4870 X2. ATI’s reference design had it disabled and all vendors followed suit.
Sideport was Carrell Killebrew’s favorite feature, and he had to give it up.
In early 2008 ATI realized they had to cut this chip down from 20 - 22mm on a side to 18mm, everyone had to give up something. Carrell was the big advocate for making 870 smaller, he couldn’t be a hypocrite and not give anything up.
A bunch of my conversation with Carrell at this point had to go off the record. Sideport would have been useful in RV870, but it’s unfortunately not there. Although he did tell me not to be surprised if I saw Sideport again at some point. Carrell doesn’t give up easily.
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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!