After the earlier silly debates, I decided to post my own experience of the 5850 vs 5870. I have owned both cards and tested them on the same system so I am better placed than most to provide a fair comparison.

PLEASE - No bickering within this thread. Keep it clean and constructive.

My System
ASUS P6T-SE Mobo (flashed to P6T)
i7 920 C0 Processor @ 3.8GHz
6GB OCZ PC10666 DDR3 RAM
Corsair HX850W PSU
Antec Six Hundred Case
Win7 64 Home Premium
*ASUS 5850 (clocks to 1000core @ 1.25v / 1200mem)
*ASUS 5870 (clocks to 1000core @ 1.3v / 1300mem)

The Tests
Here are the results of 3DMark Vantage tests performed at varying speeds. MSI Afterburner was used for clock and voltage tweaks because it is easier to use than ASUS Smart Doctor.

Test 1 - Both Cards at stock settings


Test 2 - Both Cards at 5870 speeds (850core / 1200mem)


Test 3 - Max OC 5850 vs Stock 5870


Test 4 - Both Carda at Max OC


My Vantage Benchmark Links
ASUS 5850 Stock
ASUS 5850 OC to 5870 speeds
ASUS 5850 OC to 1000core / 1200mem
ASUS 5870 Stock
ASUS 5870 OC to 1000core / 1300mem


My Opinion (others are free to differ)
*For anyone that does not overclock there is a large difference between both cards performance. The 5870 is >20% faster.
*At the same clock speeds the 5870 is about 5% faster overall. In shader intensive tests this increases to ~10%, which is to be expected because the 5850 has 10% less shader cores.
*When both cards are overclcoked to the max there remains a ~5% advantage to the 5870.
*For anyone who overclocks, the 5850 offers much better value. 5% more performance currently costs 50% more money, and unless you are either a hardcore bencher, or have money to throw away it is really not worth it.
*Core clocks on both cards reached similar levels although the 5850 required slightlly less volts. This may be due to the 5850 having 10% less shaders.
*The memory on the 5870 overclocked to 1300 vs 1200 for the 5850. This may be pure luck, but it may also be that ATI supply lower voltage to memory IC's, regulation is poorer, or the IC's themselves are not as good.
*An overclocked 5850 can easily beat a stock 5870
*Some cards will overclock different than others so mileage may vary.


edit: Crysis Warhead benches added


edit 2: A few additional observations
*The 5870 cooler is better. At 1000core the 5870 ran 5 degrees cooler than the 5850, even though the latter needs 0.05v less volts and has 10% fewer shaders to power. From memory the 5870 also felt substabtially heavier.
*The extra inch of the 5870 is due to better phase control. This should allow for better average overclocks and possible better longevity.
*Both of my cards may overclock higher than 1000core. I have not tried above 1.3v on the 5870 and 1.25v on the 5850 due to temps. I had no intention of martyring either card.

edit 3: Unique Heaven Demo Results
These results compare my 5850 with oweneades 5870 (my old 5870).

Settings
1680x1050
DX11
Shaders - High
Tessellation - Enabled
Anisotrophy - 4
AA - Off
Full Screen - Yes

5850 @ Stock clocks 34.2fps
5870 @ Stock clocks 40.4624fps
difference 18.31%

5850 @ 5870 clocks 39.8fps
5870 @ Stock clocks 40.4624fps
difference 1.66%

5850 @ Max 1000/1200 clocks 44.7fps
5870 @ Stock clocks 40.4624fps
difference -10.2%

5850 @ 925/1200 clocks 42.3fps
5870 @ 925/1250 clocks 43.4fps
difference 2.6%
*attempted bench at 1250mem for my 5850 crashed during test 10. Mem clocks left at 1200.
*5850 benched on Win7 64, 5870 on Vista 64. This may contribute to the small differences.

edit 4: Only ASUS & MSI 58xx cards officially support voltage tweaking
If you want to overclock your 5850 to 5870 levels and above you will need a few things

i) A 5850 BIOS that allows clock speeds above normal CCC levels and voltage tweaks. Currently only ASUS and MSI cards include such BIOS, although all 5850's are physically the same. If you do not purchase one of these cards you will need to flash the BIOS and risk voiding your warranty.
ii). A utility that can alter GPU volts. MSI Afterburner is currently best IMHO.
iii). A card with GPU and memory that can handle the speed.

To keep things easy, I suggest buying MSI or ASUS. If you own a different card, or have no qualms flashing BIOS you can Google "5850 BIOS Flash" to find dozens of guides.

edit 5: 3DMark06 Tests Added











3DMark 06 Observations
*At equal clock speeds the 5870 has a ~2% performance advantage.
*Overclocking either card shows noticeable gains within the Canyon Flight Test only. Withn other tests there is little difference, even between a stock 5850 and an overclocked 5870. This leads me to believe that for 3DMark06 my system is either i) CPU limited - my 3.8GHz i7 is too weedy, ii) this benchmark has discovered an architectual limitation of 58xx series cards, or iii) Most tests within this benchmark are too outdated for relaible results. I think iii) is most likely.

Above 3DMark06 Results Links
5850 @ Stock
5850 @ 5870 (850/1200)
5850 @ 1000/1200
5870 @ Stock
5850 @ 1000/1200

Very useful post, thanks for taking the time to do it.

Can't argue with those numbers or words such as 'better value', how much better is down to the individual and maybe I should have got 5850 Trifire May sell up my GPUs!

As you note the additional shaders on the 5870 are evident, just gotta get games to use em all up now

Edit: Of course you will still get some folk prepared to say that you are wrong whilst implying that they are right when they refer to your opinion .. the funny bit is that they won't even know that they are doing it and just act on instinct ...

Thanks for taking the time to do this, it will definatly help a lot of people

Well done. Confirms the findings posted over at xtremesystems some months ago.

At the same clocks the 5870 out-performs the 5850, but not by the theoretical (based on shader count) margin.

Good post, thanks for taking the time

As you say, most people will struggle to get to 850 core let alone 1000 core.

Very informative and useful, thanks.

Top marks for such a comprehensive comparison, thanks...

...for making my purchases seem pointless!

Good work, should hopefully be useful to nullify that awful other thread! However there will be the inevitable "where are the minimum frame rate" results!

So texture fill and pixel shader score show that as games start to use more complex shaders, the difference should increase.

OrphanBoy said:

Good work, should hopefully be useful to nullify that awful other thread! However there will be the inevitable "where are the minimum frame rate" results!

Click to expand...

You just asked the question .... subtle!

Top thread. Awesome piece of work, very much appreciated.

Great post, should be stickied!

Great post and a good comparison.

I have the following comments to make though.

1. I think it ws bad luck with the 5850 not hitting 1300 memory as mine does. However, how much difference would that make to the results? It would be interesting to see the 5870 run at 1000/1200 as a comparison. Perhaps it was only the difference between the 4.6% and the 4.75%.

2. I have seen lots of reviews which state that for the same overclock the 5850 require less voltage than the 5870 so your result seems valid and your theory may hold water. Equally perhaps with a 5850 needing less voltage and has less shaders that a higher maximum overclock may be acheived on the 5850?

3. Although it is a fantastic start and a great comparison it's a shame you didn;t still own both of them and could have done a few game comparisons at the same settings you used for Vantage.

4. Lastly, your results show that the increases in vantage are linear to the oc so if you find a good overclocking 5850 (like mine at 1100/1300) then overall it will be the same speed as a 5% slower clocked 5870 eg 1045Mhz and even on shader intensive games/benhcmarks it will match a 990Mhz 5870.

I am surprised at how people are debating all these benchmarks. When ATI released the 5870 and the 5850, they said that the 5850 was the same as a 5870 except for some shaders and stuff. The 5870 is, truly, an enthusiest card, and the 5850 is a little bit slower, but still very fast. Much like the Core i7 975 is a bit better than the Core i7 920.

Great job!

Prof. Cheese said:

Great post, should be stickied!

Click to expand...

+1

the memory clock makes alittle differents .

u should clock both cards to 1000/1200 then see what result u get.

but tbh we knew the 5850 isn't far behind the 5870.

JeffyB said:

Very useful post, thanks for taking the time to do it.

Click to expand...

+1 this should be a sticky imo VERY helpfull post

good job, i'm glad that i own a 5870.