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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papapapapapapapababy - Sunday, February 14, 2010 - link
Ok, ok, great read, but i have to hate a bit, 1,2,3 GO! hey Carrell here is my top priority feature for your next PRS1 -Drivers that dont suck ass-
"The performance was still a problem and the RV740 was mostly lost as a product" ...
the fuk? the 4770 is the BEST card i ever had, PERIOD. cheap, fast, cool, the perfect RV770, thanks !
bla bla Carrell "He’s single handedly responsible for getting Eyefinity included in the Evergreen stack"
Meh? who gives a sht. , Carrell give me console like gpu scaling, so we can finally play crysis at 1080p, another one for that PRS
"Carrell went to David Glenn, head of software engineering at ATI and asked"
drivers that dont suck, please?
" There were also game compatibility concerns that made ATI not interested in the software approach"
Lol i wonder why? i think i know why. Hardware, hardware, what about the software,Carrell?
ok, thats it. not much to complain this time, flawless job ati guys
f0d - Sunday, February 14, 2010 - link
long time reader/first time postingive never felt the need to post anything but with this article i really wanted to say:
"thank you"
the insights we get in these articles is amazing (i also read the first when it was done)
i like the "no technical or maketing bs" writing of this story and all the little pieces of information like with the eyefinity story and sideport
please do as much of these type of stories as possible - it must be difficult to talk to the right people and get the right information out of them and also be allowed to publish it but it makes a great read
Robert Kooijman - Sunday, February 14, 2010 - link
Awesome article Anand!Also specially created an account to inform you how impressed I am with articles like these. A real treat these behind the scenes stories in non-marketing language. Keep 'm coming, compliments!
- Friday, February 19, 2010 - link
bravowhen do the (tech industry) book's come out??
Kryten - Sunday, February 14, 2010 - link
Informative, interesting, inspirational, edifying and very well written. Here's hoping for more research and articles like this.greenguy - Sunday, February 14, 2010 - link
Hi Anand, I've been reading your stuff for 3 years or so, I just created an account to tell you how awesome that article was. Very nice work. This sort of content is why I read Anandtech. (My other favorite articles have been the SSD articles and the i5-750 article.)I especially like to hear about AMD/ATI - I like having a serious competitor to Intel out there, and I commend AMD for opening up their graphics card documentation. I hope that they continue to fund the Linux driver development (both open and closed source). I also hope their CPU division can put the heat on Intel again, especially on the low power front.
at80eighty - Sunday, February 14, 2010 - link
Anand I was just telling someone yesterday how I wish you guys got more popularity for the different approach you guys havebetween articles like this and the new beta Bench tab - I think I'm really looking forward to your proposed changes you promised this year
insurgent - Sunday, February 14, 2010 - link
I had a really great time reading the article, thanks!Markstar - Sunday, February 14, 2010 - link
Also a big thank you from me for this wonderful article.It's exactly these kind of stories that I hope to find here every morning when I start the day.
JimmiG - Sunday, February 14, 2010 - link
Well the late changes would explain why the RV870 isn't "perfect" like the 770 was. At every price point except at the high-end, it delivers more features, but less or similar performance as the previous generation. For example the 5770 is slower than the 4870, the 5750 is about the same speed and price as the 4850 and so on. Also at the high-end it's more expensive than the 4800-series ever were - the 4870 was only $299 at launch, the 5870 is still at least $399. By this month in 2009, the 4870 was down to $249!