if the 5850 clocks to performance of the 5870

[Zinthar]

Originally posted by: Just learning

I've seen one benchmark (in the form of a simple graph) where a 878 Mhz 1440 shader HD5850 actually did better than a 1600 shader @ 850 MHz HD5870......but the HD5850 had its memory @ ~1400 Mhz.

This tells me that in that testing scenario memory bandwidth was the bottleneck....not GPU power.

Let me see if I can find the graph. I am sure it was probably 2560x1600 with heavy AA/AF for that to happen though.

From what I've read in this thread: http://www.xtremesystems.org/f...howthread.php?t=235181, it seems that neither memory bandwidth nor core speed are exclusively the bottleneck on the 58xx so far.

I think it would be errant to suspect that AMD would have so badly miscalculated the bottleneck of the card to the point where the thing was only memory bandwidth-starved -- they know that consumers for high-end graphics cards are going to see the benchmarks in modern games...

 

[cbn]

Originally posted by: Zinthar

Originally posted by: Just learning

I've seen one benchmark (in the form of a simple graph) where a 878 Mhz 1440 shader HD5850 actually did better than a 1600 shader @ 850 MHz HD5870......but the HD5850 had its memory @ ~1400 Mhz.

This tells me that in that testing scenario memory bandwidth was the bottleneck....not GPU power.

Let me see if I can find the graph. I am sure it was probably 2560x1600 with heavy AA/AF for that to happen though.

From what I've read in this thread: http://www.xtremesystems.org/f...howthread.php?t=235181, it seems that neither memory bandwidth nor core speed are exclusively the bottleneck on the 58xx so far.

I think it would be errant to suspect that AMD would have so badly miscalculated the bottleneck of the card to the point where the thing was only memory bandwidth-starved -- they know that consumers for high-end graphics cards are going to see the benchmarks in modern games...

Okay....but then what about minimum frame rates? How well is HD5870 holding up compared to HD4890 in crossfire when "game demand" is at maximum?

 

[Zinthar]

Originally posted by: Just learning

Okay....but then what about minimum frame rates? How well is HD5870 holding up compared to HD4890 in crossfire when "game demand" is at maximum?

That's a great question, and one which I'm not qualified to answer.

 

[MrK6]

Originally posted by: Just learningI've seen one benchmark (in the form of a simple graph) where a 878 Mhz 1440 shader HD5850 actually did better than a 1600 shader @ 850 MHz HD5870......but the HD5850 had its memory @ ~1400 Mhz.

This tells me that in that testing scenario memory bandwidth was the bottleneck....not GPU power.

Let me see if I can find the graph. I am sure it was probably 2560x1600 with heavy AA/AF for that to happen though.

It'd be nice to see that benchmark, but you have to remember that the memory was running almost 17% faster. Considering the cores were probably <10% difference in processing power at those frequencies, it's understandable for the HD5850 to meet or beat an HD5870 under certain circumstances.

Originally posted by: Just learningOkay....but then what about minimum frame rates? How well is HD5870 holding up compared to HD4890 in crossfire when "game demand" is at maximum?

It's much better than a GTX295, if you want to extrapolate from there.

 

[lopri]

Thank you @Tempered81 for the voltage information.

 

[Assasjin]

5870 still has more stream processors

 

[bunnyfubbles]

Originally posted by: Assasjin
5870 still has more stream processors

yes, but after we overclock both cards to reasonable maximums (say 1000MHz GPU, 5000MHz RAM), the 5850 will be at worst ~90% of the 5870 for ~68% of the price

 

[MrK6]

Originally posted by: Tempered81What a great post, thank you MrK6.

Glad you found its useful :thumbsup:

Originally posted by: bunnyfubbles

Originally posted by: Assasjin
5870 still has more stream processors

yes, but after we overclock both cards to reasonable maximums (say 1000MHz GPU, 5000MHz RAM), the 5850 will be at worst ~90% of the 5870 for ~68% of the price

Who says the 5850 can match the 5870 though, no matter how many volts you give it? I mean, there's a reason they're 5850s.

 

[Tempered81]

Right. The 5850's are being lower binned cypress chips that require higher voltage to reach the 850mhz mark, or can't reach that mark at all with the 1.162 set voltage max for the 5870. Also, it seems that 5870's are coming with different stock voltages 1.120v-1.165v(must be something like VIDs for intel cpus) while the 5850's run at 1.09v 3D. Some cypresses just run at higher clocks than others and need a varying range of voltage to do so. If SPs are defective and have to be cut down, then it's obv going to be a 5850, if it can't make the cut for required volts at 850mhz, then it's also obv going to be branded a 5850. Your best luck would be to have a 5870 that can do 1000mhz on stock volts (1.12-1.17) - that would be the cream of the crop. Your worst luck would be to have a 5850 that can barely do ~775mhz with 1.09v and runs hot while trying it. The lucky dudes like Peter tan get to sift through samples all day to find the ones that can do super high clocks on super low volts with super low temperatures. That's probably how he got his 5870's core to 1400mhz with 1.65v

 

[lopri]

Originally posted by: MrK6

Originally posted by: lopri
@MrK6: How do you like your 5870 @2560x1600? Gaming-wise, and video-wise? I read from 5870 review AMD did some tweaks to its UVD2 engine. Is it something you notice while playing back HD clips?

From my BIOS read-out I get 0.95V, 1.063V, and 1.162V. So, my guess is that's your 2D idle, 2D Perf, and 3D Perf respectively. There's a total of 7 clock info modes listed in the BIOS (as opposed to 9 in the 4870). Idle is 157/300, and there's 850/1200 for full speed. There's also three other modes listed - 600/900 @ 1.063V, 400/900 @ 1.063V, and 400/1200 @ 1.063V. If I had to take a stab at guessing which they are, just based on what I know of the card and what I've read, 600/900 is throttling, 400/900 (labeled UVD) is for playback, and 400/1200 is for dual displays.

I don't actually use my computer for any high-def playback (I watch a regular DVD maybe once every two months), so I really can't comment on it's performance. Game-wise, it's amazing. The drivers still need work as I don't think the card is getting as much performance as it should be, but that'll come. I "side-stepped" over from my GTX295, and I have to say there's a marked improvement in gameplay quality, especially with "smoothness" and flow. The overclocking capabilities of such a new chip are also impressive, especially considering the ease of software voltage modification. I'm still tinkering around with voltages and capabilties, but at 950MHz, this card is insane. I imagine better samples that can get to 1000MHz 24/7 with minor voltage adjustments will quite amazing.

Thank you for your response. It's very informative. One more question: What OS are you using? Not sure if you've stated it before in this thread so please excuse me if that's the case.

 

[bunnyfubbles]

Originally posted by: MrK6

Originally posted by: Tempered81What a great post, thank you MrK6.

Glad you found its useful :thumbsup:

Originally posted by: bunnyfubbles

Originally posted by: Assasjin
5870 still has more stream processors

yes, but after we overclock both cards to reasonable maximums (say 1000MHz GPU, 5000MHz RAM), the 5850 will be at worst ~90% of the 5870 for ~68% of the price

Who says the 5850 can match the 5870 though, no matter how many volts you give it? I mean, there's a reason they're 5850s.

and that reason is they're missing shaders and tmus

I'm basing my claim off of ASUS's claim that they'll allow their 5850 to achieve 1050MHz off of their overvolting while they also say their 5870 tops out at 1035MHz with overvolting. Unless they're also cherry picking 5850s, I really don't think there is much difference between the GPUs. Sure, some 5850s could be there because they've failed tests and have been binned lower, but for the most part I don't think that is the case.

As with anything related to overclocking, there's an unspoken understanding that things won't always work out perfectly for everyone. I guess that is what I failed to convey with what I've been saying about the 5850. Sure, there is risk in getting it to perform within just a few % of the 5870, but I believe that risk to be small. And also as with anything related to overclocking or not, if you want the fastest parts, you have to pay for them.

Originally posted by: Tempered81
Right. The 5850's are being lower binned cypress chips that require higher voltage to reach the 850mhz mark, or can't reach that mark at all with the 1.162 set voltage max for the 5870. Also, it seems that 5870's are coming with different stock voltages 1.120v-1.165v(must be something like VIDs for intel cpus) while the 5850's run at 1.09v 3D. Some cypresses just run at higher clocks than others and need a varying range of voltage to do so. If SPs are defective and have to be cut down, then it's obv going to be a 5850, if it can't make the cut for required volts at 850mhz, then it's also obv going to be branded a 5850. Your best luck would be to have a 5870 that can do 1000mhz on stock volts (1.12-1.17) - that would be the cream of the crop. Your worst luck would be to have a 5850 that can barely do ~775mhz with 1.09v and runs hot while trying it. The lucky dudes like Peter tan get to sift through samples all day to find the ones that can do super high clocks on super low volts with super low temperatures. That's probably how he got his 5870's core to 1400mhz with 1.65v

Again, I don't think binning like this occurs as much as we might think it does (although I'm sure AMD/nVidia would like us to). I believe plenty of 5850s would have made perfectly good 5870s but are just cut down and volt limited.

 

[Tempered81]

Originally posted by: bunnyfubbles


Again, I don't think binning like this occurs as much as we might think it does (although I'm sure AMD/nVidia would like us to). I believe plenty of 5850s would have made perfectly good 5870s but are just cut down and volt limited.

Maybe they bin, and maybe not. Wait for some more 5850 and 5870 overclocking results to give a better picture.

 

[MrK6]

Originally posted by: Tempered81
Right. The 5850's are being lower binned cypress chips that require higher voltage to reach the 850mhz mark, or can't reach that mark at all with the 1.162 set voltage max for the 5870. Also, it seems that 5870's are coming with different stock voltages 1.120v-1.165v(must be something like VIDs for intel cpus) while the 5850's run at 1.09v 3D. Some cypresses just run at higher clocks than others and need a varying range of voltage to do so. If SPs are defective and have to be cut down, then it's obv going to be a 5850, if it can't make the cut for required volts at 850mhz, then it's also obv going to be branded a 5850. Your best luck would be to have a 5870 that can do 1000mhz on stock volts (1.12-1.17) - that would be the cream of the crop. Your worst luck would be to have a 5850 that can barely do ~775mhz with 1.09v and runs hot while trying it. The lucky dudes like Peter tan get to sift through samples all day to find the ones that can do super high clocks on super low volts with super low temperatures. That's probably how he got his 5870's core to 1400mhz with 1.65v

Well, like every computer part, there will always be "golden samples." One thing I forgot to mention was that my 5870, and by extension the chips in general, love cold. In my limited testing, with the stock fan profile, 950MHz is stable with 1.262V. this is due to the profile keeping load temps <90C (usually 86-89C). However, if I put the fan on 45% constant, the card loads at ~ 75C and needs only ~1.2V to be stable at 950MHz.

Originally posted by: lopriThank you for your response. It's very informative. One more question: What OS are you using? Not sure if you've stated it before in this thread so please excuse me if that's the case.

Glad it helped you :thumbsup:. I don't believe I mentioned its but I'm on Vista Ultimate 64-bit.

Originally posted by: bunnyfubblesAgain, I don't think binning like this occurs as much as we might think it does (although I'm sure AMD/nVidia would like us to). I believe plenty of 5850s would have made perfectly good 5870s but are just cut down and volt limited.

I'd believe this to be more likely right now, when stock is limited and production is in full ramp to replace supplies as quickly as possible. Once they fine tune the manufacturing process and supply has met demand, I believe you'll probably see a bigger difference between the 5850's and 5870's. However, once the manufacturing process improves, you might see great chips for both parts. I'm just hypothesizing a couple of scenarios, as I'm not that knowledgeable on the process.