Hybrid Xfire

[W1nTry]

Interesting stuff:

ATI previews hybrid Crossfire

GPU gang bang

By Charlie Demerjian: Thursday, 13 December 2007, 2:00 PM

ATI PREVIEWED HYBRID Crossfire today, and it looks like it will sell a lot of units. It was an early test, but had some pretty compelling features for the non-hardcore gamer set.

The hybrid refers to ganging up an integrated GPU with a discrete one to give those crappy Best Buy specials the ability to game at a low, low price.

The idea is simple, if you take an integrated GPU and try to game on it, you will know the meaning of the word slideshow. The ATI 690G took gaming on an integrated part from a joke to almost tolerable, and the upcoming 780G will be much faster, 3-4x faster than that. Almost tolerable.

If you plug in a real GPU, the integrated graphics shut off to the great loss of nothing, and the worst discrete parts take it from there. Hybrid with the 780G does a few things differently. First, the integrated part is pretty solid, about the equivalent of a standalone ATI RV610 chip. This makes it tolerable, but when you plug in an RV620, it adds to the power already there, making for an uncomfortably close to tolerable gaming.

In the demo, AMD had some Radeon HD 3450s and 3470s on a 780G board. The 34xx chips ran Call of Duty 4 at about 30 FPS alone. Turn on Hybrid Crossfire and you are perilously close to 60FPS at 1024 * 768. Crysis and Unreal Tournament III were also shown off, and they all skipped a bit but ran quite well in most cases.

This won't threaten 3870 sales, but then again, you are talking budget integrated graphics boards in the $70-120 range with a $50 add-in card. You can't beat that for price, and if you need more, there will be a range of SKUs, most likely three 780G variants at launch, and at least two RV620 cards.

In the end, performance won't stun you, but it won't be as disappointing as integrated GPUs of the past. You can plug in many GPUs, basically all 3xxx cards should work, but it will step them down to the speed of the slowest part, in this case the 780G. If you put in much more than a 36xx part, it will step down to slower than the card alone, but it should work. Stay tuned to the message boards, you know there will be at least one moron out there who does this and brags about it. Mock him.

There are some interesting tricks that you can pull with Hybrid Crossfire that are unavailable with normal cards. Other than the 780G supporting two monitors and a second GPU adding two more, they team up in some new and different ways. The card that you plug the monitor into becomes the master, and when the need for speed goes down, the machine will idle the slave part to save power. This is a carry-over from the laptop hybrid variants, and what it means is that controller location does not matter.

Initially, this power saving is driver controlled, but over the next year, there will be more additions to the tech allowing it to pull more tricks like passing data across bus so you can more or less put the master card to sleep and drive video from the slave if that would save power.

Stay tuned here, there are going to be some interesting tricks that will are rolled out. All 3xxx parts should support this as well, and it will be marketed under the powerplay name.

The parts will start coming out in January with the 3450 and 3470 being out first late in the month. Soon after, 780G parts will be out, but the official launch will be in the CeBit time frame. With the parts, the driver support will come through, and more tricks will come out over the following months.

Last, we come to an interesting technical addition called Sideport. What this is is a single optional memory chip on the motherboard that acts as a local frame buffer. You can have from 16-128M of memory, most likely DDR2, and it acts like local memory for the integrated graphics.

In the end, ATI did two things we liked, made an integrated graphics part that could get out of it's own way, and on top of it, added a bunch of technical tricks. We think the tricks will be the most useful for geeks, and they will undoubtedly trickle down to the rest of the line in one way or other.

For ATI, having its name associated with the only integrated GPU that does not blow for games is the biggest win. Who knows, AMD might even be able to turn it into a selling point. µ

[Prowl]

Me thinks there is more to this than meets the eye !

This might also be away to get more cards/devices to crossfire as well.

[W1nTry]

You're right prowl, there is more than meets the eye. Remember in Eons past where Nvidia promised SLI would work with different cards? and it turned out all they meant were different brands with similar firmware? or remember when ATI promised Xfire with any card? well it seems they are one step closer to making it a reality. Try mixing and matching 38xx series cards of various ram sizes and clocks, here's a review of their latest driver (soon to be released) 8.2:
http://www.fudzilla.com/index.php?option=com_content&task=view&id=5641&Itemid=1
It seems to allow the mixing and matching of cards, but the gain isn't quite there yet. Still very promising!

[Philosophical45]

that's very interesting.. seems like ati is taking a step up in towards improving their technology. Mixing and matching cards is a very sensible move, providing that the end user doesn't get two of the same cards and still wants to pair them up in crossfire. It will be interesting to see Nvdia's response to this move from ATi.