The ATI HD 5750 in the iMac is a mobility 5850.

Discussion in 'iMac' started by TMRaven, Jul 27, 2010.

  1. macrumors 68020

    TMRaven

    Joined:
    Nov 5, 2009
    #1
    Thanks to our member dwd3885, who went to an apple store to get a brand new high end iMac, we have good evidence of the advertised 5750 in the new high end iMac as being mobility 5850. This is neither good or bad news-- but could be considered as better news rather than worse news. The current speculation was an underclocked desktop 5750, which would provide same performance as mobility 5850.

    dwd3885's system profiler has marked the ati 5750's device id as 0x68a1, and thanks to our member Horus' link, we are able to get a good idea that the 5750 is actually a mobility 5850. Also, due to Hellhammer's great research, this shows the ox68a1 model to be BroadwayPro/LP, which are both mobility 5830 and mobility 5850. Since mobility 5830 can not use GDDR5 memory, the only logical solution would be mobility 5850.

    Thanks to our member easepease, we now have image confirmation from gpu-z that the gpu in the new high end iMacs is in fact a default-clocked mobility 5850.

    [​IMG]

    How does the mobility 5850 compare with the mobility 4850 in the older high end iMac? About the same. Notebookcheck has the mobility 5850 with GDDR5 being at a slight edge over mobility 4850. New iMac users do get some added benefits as well. Raw processing power and memory bandwidth performance are virtually the same, however a bigger memory buffer will help games with running higher textures and detail, especially at such a high resolution. The higher memory buffer will also help memory intensive applications.

    The mobility 5850 will also consume a good chunk power less than mobility 4850 due to newer technologies and better throttling (39 watts vs 60 watts), so users will experience a cooler iMac. Also considering mobility 5850's relative cool output, it will be quite easy to overclock it closer to mobility 5870 standards, which is basically a slightly higher clocked mobility 5850.

    This also probably means the advertised HD 5670s in other iMacs are mobilie 57** cards.



    Some food for thought:
    Notebook check has the 1gb GDDR5 version of mobility 5850 playing Bad Company 2 at x resolution with ultra settingss rated at 31fps.
    Notebook check also has the 512mb GDDR3 version of mobility 4850 (but with 575mhz core clock compared to the 500mz in iMac) at 25fps. If the same core were to be underclocked to 500mhz, we could expect around 20-25fps.



    Comparison of two cards' memory bandwidth performances:
    mobility 5850: 128bus width/8bytes x 1000mhz sdram clock rate x GDDR5's quad data rate of 4 = 64gbps of memory bandwidth.
    mobility 4850: 256bus width/8bytes x 850mhz sdram clock rate x GDDR3's double data rate of 2 = 54gbps of memory bandwidth.

    As you can see, with 15% greater memory bandwidth and a more efficient processing core, the mobility 5850 with GDDR5 memory will perform around 10% greater than mobility 4850.

    The mobility 5850 is a 10% slower clocked mobility 5870, so users who want the most out of their gpu could safely overclock to mobility 5870 range under windows-- mobility 5870 is 20% more powerful than mobility 4850, according to notebookcheck.
     
  2. macrumors regular

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    #2
    Thanks for doing the leg work! If that is true then at least it isn't a downgrade.
     
  3. macrumors Penryn

    Eidorian

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    #3
    It's not fun to play this game with hardware IDs every time there is an iMac update. Apple should just admit they're using Mobility GPUs.
     
  4. macrumors 6502

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    Nov 29, 2009
    #4
    Double the VRAM at double the speed, slightly better gaming performance and less heat? Sounds good to me.
     
  5. thread starter macrumors 68020

    TMRaven

    Joined:
    Nov 5, 2009
    #5
    Some food for thought:

    Notebook check has the 1gb GDDR5 version of mobility 5850 playing Bad Company 2 at x resolution with ultra settingss rated at 31fps.
    Notebook check also has the 512mb GDDR3 version of mobility 4850 (but with 575mhz core clock compared to the 500mz in iMac) at 25fps. If the same core were to be underclocked to 500mhz, we could expect around 20-25fps.
     
  6. macrumors 6502

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    Oahu
  7. macrumors member

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    Jul 27, 2010
    #7
    Don't they also say that the GDDR5 makes a huge difference?

    I think the 1G vram + the GDDR5 should in theory make for a speed boost.
     
  8. macrumors regular

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    #8
    Whatever the case, for me it is a major upgrade. I'm running on a PowerBook G4. I can hardly play pong.
     
  9. macrumors 6502

    Joined:
    Nov 29, 2009
    #9
    I'm running an underclocked Radeon 9200 with an earth-shattering 32 MB of VRAM on my first-gen Mac mini. The 2.93 i7 will literally be at least a 15x speed boost!
     
  10. macrumors member

    Joined:
    Jul 27, 2010
    #10
    Yeah, easy decision for you.

    I'm really having trouble with the switch from my custom PC that I built about 2.5 years ago. I'm running a quad core with an 8800 GT which is still a beast system.

    However, I love OS X and I think the 5850M should be on par with what I am running now.
     
  11. macrumors regular

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    #11
    Good feeling isn't it? I'm ordering mine probably Friday. Having a decent GPU would just be an added benefit. I really need a computer with multi-core processing for audio. My G4 just doesn't cut it anymore.
     
  12. thread starter macrumors 68020

    TMRaven

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    Nov 5, 2009
    #12
    No, because the mobility 5850 has a 128bit bus width, while the mobility 4850 has a 256bit bus width. Memory bandwidth performance is found by multiplying the multiple clocks together with bus width. Since GDDR5 is roughly twice as fast as GDDR3, but 128bit bus is only half of 256 bit bus, both cards have roughly same amount of memory bandwidth and rendering power.

    mobility 5850: 128bus width/8bytes x 1000mhz sdram clock rate x GDDR5's quad data rate of 4 = 64gbps of memory bandwidth.
    mobility 4850: 256bus width/8bytes x 850mhz sdram clock rate x GDDR3's double data rate of 2 = 54gbps of memory bandwidth.
     
  13. macrumors newbie

    Joined:
    Jul 27, 2010
    #13
    Thx for the info guys. So if a refurbished late 2009 i5 model was an option, it would have similar game performance but cheaper?
    Ofcourse the new iMacs have slightly better CPUs and Ram though correct. But these factors wont help gaming as they are not the bottleneck right?
     
  14. macrumors regular

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    #14
    I can see how that would make you apprehensive. I have never owned a PC and all of my gaming has been on consoles. Having a computer with above average gaming capabilities would be awesome but I'll settle for what I can get.
     
  15. macrumors 65816

    henrikrox

    Joined:
    Feb 3, 2010
    #15
    Dont understand why they didnt sprung for the 5870 mobility.

    i mean mobility 5850 is on on 32 place
    whule 4850 is on 25 place
     
  16. macrumors newbie

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    Feb 15, 2008
    #16
    How will it compare to the other standard GPU option?
     
  17. macrumors member

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    #17

    I was actually going to ask a semi-related question on this. I've got a late 08 Mac Pro which has the 8800 in as well- and assuming the new iMac does in fact have a mobility 5850 - how would these two GPU's compare when it comes to say gaming? (Yes, I know macs aren't "gaming machines" and that's not my primary use for it, but we all need some downtime right :)) - I was struggling to find anywhere which would compare desktop and mobile GPU's even if it wasn't 100% accurate.
     
  18. Moderator emeritus

    Hellhammer

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    #18
    Thanks for the work TMraven. Actually, it's a good thing if it's mobility 5850 as it has 800 stream processors while desktop 5750 has 720. Now we just have to wait for someone to install Windows and GPU-Z to know the exact clocks
     
  19. macrumors member

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    Sep 3, 2006
    #19
    In the previous generation it was mobile 4670, if they put a 5750 in new generation its a big upgrade no ?
     
  20. Moderator emeritus

    Hellhammer

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    #20
    Mobility = underclocked desktop version

    So it COULD be desktop version but heavily underclocked but more likely mobility 57xx which is basically same as underclocked desktop 5670.
     
  21. macrumors member

    Joined:
    Sep 3, 2006
    #21
    So we get (to be confirmed) a big GPU upgrade in the 21,5" (from 4670M to 5750M) and a slight upgrade in the 27" (from 4850M to 5850M=5750D) ?
     
  22. Moderator emeritus

    Hellhammer

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    #22
    Yea, the update should be bigger in 21.5" but we still need to clock to know what exactly is it (if it's mobility 5650, Apple can take a hike)
     
  23. macrumors 65816

    henrikrox

    Joined:
    Feb 3, 2010
    #23
    A bit confused here now

    So to summarize the card can either be a desktop 5750 (just underclocked)

    or

    a mobilti 58xx series?

    any chance it could be a 5870 mobility? or is it likely to be a 5850 since apple called it 5750

    and Please people, post the clocks
     
  24. Moderator emeritus

    Hellhammer

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    #24
    The device ID hints that it's mobility 58xx. Whether it's 5850 or 5870, we don't know yet.
     
  25. macrumors 65816

    henrikrox

    Joined:
    Feb 3, 2010
    #25
    Ah the suspense is killing me, wasn't 5870 mobility the fastest mobile gpu before geforce launched its fermi based mobile lineup?

    Im excluding mobile crossfire/sli setups
     

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