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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n7 - Sunday, February 14, 2010 - link
Another great story told.Thanx, Anand.
MrK6 - Sunday, February 14, 2010 - link
What a great piece. Thank you for taking the time to put this together; it's one of the best tech articles I've read.archcommus - Sunday, February 14, 2010 - link
Haven't even read the whole thing yet but I can already say this is excellent. Thank you, Anand.indicator - Sunday, February 14, 2010 - link
Hi allI felt I had to register here after reading this article , what a fantastic insight into everything that goes into making these GPU's and the dedication and talent it takes to be so creative.
Great to see Anands enthusiasm for the industry come across in the article too
I've been coming here and reading Anandtech since around the mid ninties I guess , it is a superb source of information , I look forward to every new article/review posted.
Keep it up guys
Lee
(uk)
d3x7r0 - Sunday, February 14, 2010 - link
Very very good article as usual in this website. AnandTech has been one of my favourite sites in the area for so long I don't even remember how I found out about the website, I actually believe I was still in 56k when I first came here.Anyway reading this article made me speculate on something (and please correct me if I'm wrong): If I got the timings right AMD-ATI should be working on the Northern Islands since the Radeon HD4xxx series days so the same issues they had with the HD5xxx series would be in the past. If this is true it means they know the HD4xxx were a success from the beginning of the process (or near it) and as such I can't but help it be even more excited to see what the next generation of ATI cards has in store.
It's such a good time to be an ATI fan it's not even funny :D
Atlantis6000bc - Sunday, February 14, 2010 - link
Those kind of article are the prime reason why I keep coming back to Anand....keep 'em comingThe13thWizard - Sunday, February 14, 2010 - link
Thanks Anand! Thats the best IT article Ive ever read! Very toughtfull and interesting!arnavvdesai - Sunday, February 14, 2010 - link
Really helps understand the industry a lot more. I really wish AMD would take a cue from its graphics division and really start hammering out what kind of chips do they want to build. However, they have their own set of challenges as Intel unlike NVIDIA is really really good on the foundry side as well.However, with gaming becoming more and more centered on consoles, does ATi have something cooking for the next generation of consoles? Would love Anand to ask them something about that. Do they believe that they will continue to sell enough cards to continue recouping their costs of designing and manufacturing them.
Vishnu Narayanan S - Sunday, February 14, 2010 - link
First of all, hats off to you for this amazing article.... Its these articles that bind us to the Anandtech website for years and years.I sincerely hope and request you to provide similar in-depth and "behind the scenes" stories from NVIDIA and Intel. Just to satisfy the FANbois... lol
fausto412 - Sunday, February 14, 2010 - link
once i started reading i couldn't stop. for a geek like me this was almost like sex:) keep them coming!