Radeon HD6790 (Barts LE) review

[Lorien]

Pctuning posted a review for a short time and quickly pulled it. Here's a mirror of the images posted in the article.

The card looks to be pretty much identical to slightly faster than the GTX550, so depending on pricing it may trigger another round of Nvidia price cuts. I wouldn't hold my breath waiting for that though, because margins are already razor thin in this segment of the market, which is why we are seeing the introduction of this new product based on salvaged dies instead of price cuts of the older (and arguably better) SKUs which would've been the more consumer friendly option.

Heatsink shroud assembly and dimensions identical to the HD6870.

That 63 fps looks to be a typo and is most likely only 53.

 

[XacTactX]

Thanks Lorien, very cool of you to grab this and host it, I appreciate it. Much better than holding our breaths for another week.

6790 = 2x 6 pin
6850 = 1x 6 pin
6870 = 2x 6 pin

This is the weirdest progression in power connectors ever in my opinion. A faster card needs less PCIe connectors than a slower one. It could actually hurt the penetration of this card, people in this card's price point don't generally have a bunch of leftover PCIe connectors; Some will not be able to support CrossFire, others may not be able to get one at all, and will get a 6850 instead.

 

[Evil Penguin]

They had to disable 320SPs?
Lame.

 

[Rizen]

They had to disable 320SPs?
Lame.

Have to? No. They probably just picked the lowest number needed to put the card in the priceerformance bracket, and rolled with it, since that way they can use the largest number of less quality dies.

 

[jeremyshaw]

Thanks Lorien, very cool of you to grab this and host it, I appreciate it. Much better than holding our breaths for another week.

6790 = 2x 6 pin
6850 = 1x 6 pin
6870 = 2x 6 pin

This is the weirdest progression in power connectors ever in my opinion. A faster card needs less PCIe connectors than a slower one. It could actually hurt the penetration of this card, people in this card's price point don't generally have a bunch of leftover PCIe connectors; Some will not be able to support CrossFire, others may not be able to get one at all, and will get a 6850 instead.

same thing with the HD5830, lol. I'm still wondering why they didn't call it the HD6830, for that matter....

 

[Spooony]

Wizard probably already busy checking what unlock goodies Amd is hiding away

 

[Lord_Exodia]

At around 150 Watts they could have used only one 6 pin power connector. Rumors are circulating that this card uses the same pcb as the 6870 and that the card may unlock the additional SP's. I'm not sure if it'll unlock to 6850 or 6870 types of speeds but either proposition could make this a great value, and could explain the reason for a 2nd 6 pin

http://www.fudzilla.com/graphics/item/22273-amd-radeon-hd-6790-is-a-great-overclocker

Just imagine for a minute a 1000mhz core 6870 for $149.99

 

[XacTactX]

At around 150 Watts they could have used only one 6 pin power connector. Rumors are circulating that this card uses the same pcb as the 6870 and that the card may unlock the additional SP's. I'm not sure if it'll unlock to 6850 or 6870 types of speeds but either proposition could make this a great value, and could explain the reason for a 2nd 6 pin

http://www.fudzilla.com/graphics/item/22273-amd-radeon-hd-6790-is-a-great-overclocker

Just imagine for a minute a 1000mhz core 6870 for $149.99

That would be pretty sweet, the 6790 would be to the 6870 what the 6950 is to the 6970. For some reason I doubt it though, they cut the shaders on the chips that are to be branded as the 6850, why would they remove the shaders for certain models but not for others? But I'm just playing devil's advocate/speculating, it would be great if that happened.

 

[Ehren8879]

At around 150 Watts they could have used only one 6 pin power connector. Rumors are circulating that this card uses the same pcb as the 6870 and that the card may unlock the additional SP's. I'm not sure if it'll unlock to 6850 or 6870 types of speeds but either proposition could make this a great value, and could explain the reason for a 2nd 6 pin

http://www.fudzilla.com/graphics/item/22273-amd-radeon-hd-6790-is-a-great-overclocker

Just imagine for a minute a 1000mhz core 6870 for $149.99

I can imagine a pair of them! Serious value right there no matter how you look at it.

 

[Lorien]

At around 150 Watts they could have used only one 6 pin power connector.

Nope, they are using salvaged chips just like in the HD5830, GTX465. Salvaged chips require more power to activate the fewer functional units they have. These chips were not good enough to be 6870s, they didn't even pass testing to be 6850s either so they increased voltage (and thus TDP) to activate an even more reduced number of SMs.

Rumors are circulating that this card uses the same pcb as the 6870

What rumors lol? Look at the pictures I posted, I already proved it uses the same PCB as Barts XT (6870).

and that the card may unlock the additional SP's.

Nah, again the 6790 is made from SALVAGED chips that were not good enough to be 6850/6870s. They NEED the extra voltage to operate, and it is more likely they will not unlock. The 6950 unlocks only because of very high yields of Cayman, the 6790 is completely the opposite. The chips used in it are the ones belonging to the bad yielding pile and would've otherwise been thrown to the recycling bin.

I'm not sure if it'll unlock to 6850 or 6870 types of speeds but either proposition could make this a great value, and could explain the reason for a 2nd 6 pin

Unlocking is very much doubtful and considering the 6850 overclocked really well it's probably safe to assume these chips can overclock as well but the voltage and TDP are already pretty high so there won't be much headroom. 1000Mhz out of this card sounds like a stretch.

Quite honestly, this card is not really a good value for consumers. Just like the HD5830 and GTX465 they are a way to recover some cash since those chips would've been thrown to the recycling bin. I saw a good analogy of this card at beyond3d. This card is like a restaurant made a dish from their table scraps and rotten ingredients, dressed it up with lots of garnish and sold it at nearly the same price as a dish prepared from scratch.

If they really wanted to give good value to consumers they would've lowered prices of the 6850, but no, they chose to introduce a new product made from their table scraps to keep prices of the 6850 artificially high. It will still sell simply because it beats the GTX550 while costing about the same but those who know better should just wait for sales/rebates on the higher end SKUs.

 

[TomGreen321]

At around 150 Watts they could have used only one 6 pin power connector. Rumors are circulating that this card uses the same pcb as the 6870 and that the card may unlock the additional SP's. I'm not sure if it'll unlock to 6850 or 6870 types of speeds but either proposition could make this a great value, and could explain the reason for a 2nd 6 pin

http://www.fudzilla.com/graphics/item/22273-amd-radeon-hd-6790-is-a-great-overclocker

Just imagine for a minute a 1000mhz core 6870 for $149.99

I doubt it. Pretty sure the reference 5830's were on 5870 pcbs and you couldn't unlock those.

 

[evolucion8]

Nope, they are using salvaged chips just like in the HD5830, GTX465. Salvaged chips require more power to activate the fewer functional units they have. These chips were not good enough to be 6870s, they didn't even pass testing to be 6850s either so they increased voltage (and thus TDP) to activate an even more reduced number of SMs.


What rumors lol? Look at the pictures I posted, I already proved it uses the same PCB as Barts XT (6870).


Nah, again the 6790 is made from SALVAGED chips that were not good enough to be 6850/6870s. They NEED the extra voltage to operate, and it is more likely they will not unlock. The 6950 unlocks only because of very high yields of Cayman, the 6790 is completely the opposite. The chips used in it are the ones belonging to the bad yielding pile and would've otherwise been thrown to the recycling bin.


Unlocking is very much doubtful and considering the 6850 overclocked really well it's probably safe to assume these chips can overclock as well but the voltage and TDP are already pretty high so there won't be much headroom. 1000Mhz out of this card sounds like a stretch.

Quite honestly, this card is not really a good value for consumers. Just like the HD5830 and GTX465 they are a way to recover some cash since those chips would've been thrown to the recycling bin. I saw a good analogy of this card at beyond3d. This card is like a restaurant made a dish from their table scraps and rotten ingredients, dressed it up with lots of garnish and sold it at nearly the same price as a dish prepared from scratch.

If they really wanted to give good value to consumers they would've lowered prices of the 6850, but no, they chose to introduce a new product made from their table scraps to keep prices of the 6850 artificially high. It will still sell simply because it beats the GTX550 while costing about the same but those who know better should just wait for sales/rebates on the higher end SKUs.

Well, if it's priced against the GTX 550 Ti, then it has value as the GTX 550 Ti has even problems trying to stay competitive with the aging HD 5770. I just hope that it doesn't use that much power, or it will be wasteful, just like the HD 5830 and GTX 465.

 

[jeremyshaw]

Nope, they are using salvaged chips just like in the HD5830, GTX465. Salvaged chips require more power to activate the fewer functional units they have. These chips were not good enough to be 6870s, they didn't even pass testing to be 6850s either so they increased voltage (and thus TDP) to activate an even more reduced number of SMs.


What rumors lol? Look at the pictures I posted, I already proved it uses the same PCB as Barts XT (6870).


Nah, again the 6790 is made from SALVAGED chips that were not good enough to be 6850/6870s. They NEED the extra voltage to operate, and it is more likely they will not unlock. The 6950 unlocks only because of very high yields of Cayman, the 6790 is completely the opposite. The chips used in it are the ones belonging to the bad yielding pile and would've otherwise been thrown to the recycling bin.


Unlocking is very much doubtful and considering the 6850 overclocked really well it's probably safe to assume these chips can overclock as well but the voltage and TDP are already pretty high so there won't be much headroom. 1000Mhz out of this card sounds like a stretch.

Quite honestly, this card is not really a good value for consumers. Just like the HD5830 and GTX465 they are a way to recover some cash since those chips would've been thrown to the recycling bin. I saw a good analogy of this card at beyond3d. This card is like a restaurant made a dish from their table scraps and rotten ingredients, dressed it up with lots of garnish and sold it at nearly the same price as a dish prepared from scratch.

If they really wanted to give good value to consumers they would've lowered prices of the 6850, but no, they chose to introduce a new product made from their table scraps to keep prices of the 6850 artificially high. It will still sell simply because it beats the GTX550 while costing about the same but those who know better should just wait for sales/rebates on the higher end SKUs.

Well, 40nm (TSMC) was already reported around the HD6800 series launch to be as mature as 55nm (TSMC), so I'd assume AMD is loosing money on potential HD6800 chips by making this market placement product...?

And the HD4830 was probably one example of a good chip (which is probably why the HD5830 was such a let down from the beginning), it was competitive vs the old 8800gt/9800gt, yet priced realistically, and still overclocked rather well.

 

[XacTactX]

I agree jeremy, that viewpoint makes more sense. I don't understand why Cayman is yielding so well that 90% of the 6950s can into 6970s, but Barts, which is a smaller and less complex chip, has such worse yields that they're making two products that cut the shaders. It would seem like the whole 40nm process should mature as a whole so if Cayman yields nicely then Barts should too. But the 6790's release tells a different tale.

 

[jeremyshaw]

lol, maybe we will see an unlockable 2GB HD6930 if this keeps on going *with* a 6pin + 8pin

 

[timme]

I like how they advertise it with "Full HD Gaming" without the card being actually useful in most games at full HD resolution.

 

[Ocellaris]

Nah, again the 6790 is made from SALVAGED chips that were not good enough to be 6850/6870s. They NEED the extra voltage to operate, and it is more likely they will not unlock. The 6950 unlocks only because of very high yields of Cayman, the 6790 is completely the opposite. The chips used in it are the ones belonging to the bad yielding pile and would've otherwise been thrown to the recycling bin.

Well look at the various AMD X2/X3 CPUs that you can unlock cores on. Presumably those all failed yield checks as well, however plenty of people have had success cranking up the voltage and getting access to the extra cores.

 

[BladeVenom]

Newegg has it in stock now for $149.99 http://www.newegg.com/Product/Product.aspx?Item=N82E16814131397

 

[XacTactX]

Those display outputs are really meager compared to what they've been doing with all the other 6000 cards. I wonder if the reference design will have those display outputs. On the one hand, it's all you really need since they can all be adapted easily, on the other hand, it's not what we're used to.

 

[rUmX]

I agree jeremy, that viewpoint makes more sense. I don't understand why Cayman is yielding so well that 90% of the 6950s can into 6970s, but Barts, which is a smaller and less complex chip, has such worse yields that they're making two products that cut the shaders. It would seem like the whole 40nm process should mature as a whole so if Cayman yields nicely then Barts should too. But the 6790's release tells a different tale.

Yeah I agree it's really odd. Maybe has something to do with VLIW4 vs VLIW5?

 

[happymedium]

6790 at newegg for 157$ shipped, way way to high of a price with the gtx460 768 going for 114$ AR..

You can actually buy a 6850 cheaper AR.

 

[rUmX]

There's no point buying a 768mb card in 2011.

 

[happymedium]

There's no point buying a 768mb card in 2011.

really? 1650x1050 is the target audience for these 120$ cards. 768mb is more than enough for that res. The cards are to slow to run any demanding games at high resolution anyway. before it uses more than 768mb of memory the fps in the games will be below 30 anyway.

 

[Mr. K6]

Yeah I agree it's really odd. Maybe has something to do with VLIW4 vs VLIW5?

Could be, they might have added more fail-safes/redundancy into the redesign or made it easier to manufacture so there's fewer bad chips up front (just guessing here, I don't know much about fabs).

The other thing to consider is that this could be a pure volume issue: if AMD's been pumping out these cards for the last 6 months, and the midrange always sells in much higher volumes, they might have finally amassed enough "bad" chips to throw these cards into the market. They're a heck of a money maker for AMD. I don't see many enthusiasts buying them unless they unlock though.

 

[rUmX]

really? 1650x1050 is the target audience for these 120$ cards. 768mb is more than enough for that res. The cards are to slow to run any demanding games at high resolution anyway. before it uses more than 768mb of memory the fps in the games will be below 30 anyway.

I'm just thinking about myself here, as an enthusiast. I wouldn't buy a card with that little VRAM, whether the card is slow or not.

Could be, they might have added more fail-safes/redundancy into the redesign or made it easier to manufacture so there's fewer bad chips up front (just guessing here, I don't know much about fabs).

The other thing to consider is that this could be a pure volume issue: if AMD's been pumping out these cards for the last 6 months, and the midrange always sells in much higher volumes, they might have finally amassed enough "bad" chips to throw these cards into the market. They're a heck of a money maker for AMD. I don't see many enthusiasts buying them unless they unlock though.

That popped into my head because, on paper, a 4D architecture should be a lot less complicated to design than a 5D architecture. Pulling numbers out of a hat, the volume production ratio of Barts to Cayman is probably something like 25:1.

 

[happymedium]

I'm just thinking about myself here, as an enthusiast. I wouldn't buy a card with that little VRAM, whether the card is slow or not.
.

So 3 years ago you would have bought a 8800gt 1gb over a 8800gtx 768mb?

I don't think you would because the 8800gt was not fast enough to fully utilize 1gb of video memory just like the 6790 or gtx550, or gtx460 768 @ 1650x1050 is not.

An enthusiast would know better.

 

[rUmX]

Now you are bringing in different classes/tiers which changes the whole picture. We are talking about 2 cards that are what, $20-30 difference in price at most? Not hundreds of dollars difference that was the 8800GT/GTX. So what are you trying to prove again?

 

[happymedium]

Well my proof was in post 23 and your opinion was in post 25.
Proof wins.

 

[rUmX]

That's irrelevant. No one buying these cards will be playing that game at those settings.

 

[Mr. K6]

That's irrelevant. No one buying these cards will be playing that game at those settings.

Exactly. And why buy a card with less potential? AMD is smart here because they know RAM sells cards. I imagine we'll see the prices on the 6790's come down in a few weeks after the introduction premiums, and at that point who would consider the GTX 460 at all? Two 6790's in CF for <$250 will be an attractive option for more mid-range builds.

 

[happymedium]

That's irrelevant. No one buying these cards will be playing that game at those settings.

Exactly, thats why you will never see a video ram limitation with a gtx460 with 768mb of memory. Like I said these cards are aimed at the 1650x1050 and below res.

You can get a gtx460 768mb for 115$AR, overclock it and it would destroy a 6790's that cost 157$ a piece on newegg.

If were going to crossfire 2 6790's for 315$ , you would be better off spending 20$ more for a 6970.

 

[Lorien]

...Maybe has something to do with VLIW4 vs VLIW5?

Yup, this is it.

Cayman is VLIW4, each SM uses LESS transistors and die space than Cypress hence better yields. Barts is VLIW5 just like Cypress and thus has more transistors per SM than Cayman so yields will be relatively lower. Also AMD is not "losing more money", the chips are already made so they are already in the hole for every non fully functional chip. Why not make a product to recover those costs. Someone at AMD obviously already did the math of adding BOM materials and testing costs and found it feasible to release a product such as this.

Also think about how long has Barts been in production. The cards were released in October of last year that means chip production ramped up at least 3 months before that. Nine months is plenty of time to accumulate enough chips from the bad yielding pile to make a product launch like this possible. Yields don't necessarily have to be bad throughout the entire chip production line.