780M Overclocking

Discussion in 'iMac' started by gmbaker44, Oct 8, 2013.

  1. gmbaker44 macrumors newbie

    Joined:
    Aug 29, 2013
    #1
    Has anyone tried to overclock their 780m in the new iMac? I was reading that it comes heavily downclocked from Apple. I would like to try mine but my computer came yesterday and I'm out of town for 3 weeks on business.
     
  2. X-Ravin macrumors regular

    Joined:
    Nov 30, 2008
    #2
    Ill be looking into it soon. I know people have had luck with the 680mx

    http://www.overclock.net/t/1391430/gtx-680mx-overclock-results
     
  3. Mac32, Oct 8, 2013
    Last edited: Oct 8, 2013

    Mac32 macrumors 6502a

    Joined:
    Nov 20, 2010
    #3
    Recommended before overclocking:
    *Disable CPU turbo boost
    *Use a fan controll program (like Lubbo's fan control) to set the fan speed at a static high speed like 2500rpm (not any higher than 2600rpm).

    I use +250/+375 with only a small temp difference with my 680MX, and although also 285/425 is 100% stable with CPU turbo boost disabled, it does heat up the iMac a bit more and is not worth it for a miniscule performance boost over 250/375.

    I'm not sure what chip design 780M uses, and how it compares to 680MX, but it could be capable of overclocking even higher since 780M=100w vs. 680MX=120w.

    Looking forward to read the results! :) In Windows7 64bit, 3dmark11 highest score @ 285/425 I got is P8813/graphics 9056. (My very highest score is P8903/graphics 9248 @ 292/450, btw. stock speed =P6857/graphics 6257) However this was some months ago, newer Nvidia drivers might improve the results. I'll try the tests again soon.
     
  4. elithrar macrumors 6502

    elithrar

    Joined:
    May 31, 2007
    #4
    Thanks for the hard numbers, even if they're for a 680MX. Like you, I'm expecting that the 780M should give at least that much--if not even more--due to the cooler running normal operating temp.

    For those of you playing at home, make sure to use the latest nVidia beta drivers: http://forums.guru3d.com/showthread.php?t=381932 (331.40 beta)
     
  5. tomnavratil macrumors 6502a

    tomnavratil

    Joined:
    Oct 2, 2013
    Location:
    Litovel, Czech Republic
    #5
    Thanks for this info, certainly very useful!
     
  6. X-Ravin macrumors regular

    Joined:
    Nov 30, 2008
    #6
    OC benefits are really application specific too. I tried 260/500 OC and saw little difference on FF14 which is super CPU intensive. Temps looked ok though, 85C. Need to 3dmark it. First run without rebooting was ~P6800 at stock.
     
  7. Mac32 macrumors 6502a

    Joined:
    Nov 20, 2010
    #7
    I would recommend changing the GPU/ram overclocking ratio. I see a lot of people here overclocking the ram too high. You get pretty much no performance increase, only more heat.
    To examplify: I made two tests in 3dmark11 w/680MX:
    +292/+502 = P8903 (graphics 9258) vs. +292/450 = P8891 (graphics 9248) :)
    This is basically the same score, considering how 3dmark11 scores varies slightly between test.
     
  8. X-Ravin macrumors regular

    Joined:
    Nov 30, 2008
    #8
    Yeah I know, I had all of about 10 minutes to play so I just ramped up to what it could handle :D Looks like some good potential in that chip though.
     
  9. gmbaker44 thread starter macrumors newbie

    Joined:
    Aug 29, 2013
    #9
    I'm new to the whole overclocking thing

    What programs do you use to overclock it?
     
  10. X-Ravin macrumors regular

    Joined:
    Nov 30, 2008
    #10
    MSI Afterburner or nVidia Inspector.
     
  11. gmbaker44 thread starter macrumors newbie

    Joined:
    Aug 29, 2013
    #11
    How do you disable CPU boost in Windows?

    How do you disable CPU boost in Windows?
     
  12. malvicus macrumors member

    Joined:
    Jul 28, 2013
    #12
    This thread makes me cringe. I'd have the exact same reaction if someone tried to overclock their macbook pro retina. Sure you can spin up the fan but you still run the serious risk of overheating and ruining such a beautifully designed computer. If you must over clock, get a nice bulky PC that's not running a videocard with the same design specifications for a notebook; a cooling system for the computer; and a beautiful display that is compareable to the 27 inch iMac and enjoy.
     
  13. gmbaker44 thread starter macrumors newbie

    Joined:
    Aug 29, 2013
    #13
    Well

    If you monitor the internal temperatures are you really risking much?
     
  14. malvicus macrumors member

    Joined:
    Jul 28, 2013
    #14
    How about increased wear and tear on a fan that was most likely not intended to run at consistently high speeds for cooling down a consistently hot video card? I'll accept that there's a vibrant community of Mac overclockers, I just can't accept the reasoning behind it. I was personally impressed by how cool it runs compared to the 2011 models over long periods of time. So doing things that runs roughshod over the intended design of the iMac is mind boggling.
     
  15. Nirurin macrumors member

    Joined:
    Oct 3, 2013
    #15
    I agree with this, in the long term. However, how difficult is it to set up a GPU overclock? Would it not be possible to set up the overclock on an as-needed basis, and revert to normal settings afterwards?

    Just a thought.
     
  16. Mac32 macrumors 6502a

    Joined:
    Nov 20, 2010
    #16
    Overclocking the graphics card is pretty harmless IMO, as long as you know what you're doing. One should definately do some research first, and not overclock right at the limit before random reboots sets in. Find the threshold where you get a big performance boost without a big temp increase. For me with the 680MX this is between 225/350-250/375. I can go higher than this, but I choose not to, so I don't stress the iMac too much.
    I've been playing a lot of games the last 8-9 months, and no issues so far. :)

    Quite frankly, I would be more concerned with playing games without overclocking, but don't use fan control software and don't disable turbo boost, and getting temps at 90-100C.
     
  17. WilliamG macrumors 604

    Joined:
    Mar 29, 2008
    Location:
    Seattle
    #17
    I overclock and don't disable turbo boost or use fan control software. I've found there to be no point, and my GPU temp never gets above ~85C or so. No issues.
     
  18. Mac32, Oct 11, 2013
    Last edited: Oct 11, 2013

    Mac32 macrumors 6502a

    Joined:
    Nov 20, 2010
    #18
    Well, I didn't mean that if you overclock with CPU turbo boost you'll wreck your computer. :) IMO the iMac is a small, closed system, and if I can lower the CPU temp by 10C, that will put less strain on the system. I have the 3.4ghz i7 CPU though, the difference is likely slightly smaller with the i5 CPU.
    Same thing without a static high fan speed, I seriously doubt being able to play the most demanding computer games like Crysis 3 without getting near 90C or higher.
     
  19. X-Ravin macrumors regular

    Joined:
    Nov 30, 2008
    #19
    Why do you care if we overclock an iMac vs. a PC? And honestly overclocking is a hell of a lot safer than it was a few years ago, back before chips had quick thermal shutdowns before damage occurs. And as has been stated, you can OC an iMac and be well within temperature spec for the chips, so it's basically like a free performance boost. In fact you probably run cooler and safe with an OC'd GPU and Turbo Boost turned off. I remember benchmarking my MBPr. With turbo boost on the CPU temp would sky rocket, even completely stock.
     
  20. 2Turbo macrumors 6502

    2Turbo

    Joined:
    Feb 18, 2011
  21. Serban Suspended

    Joined:
    Jan 8, 2013
  22. elithrar, Oct 13, 2013
    Last edited: Oct 13, 2013

    elithrar macrumors 6502

    elithrar

    Joined:
    May 31, 2007
    #22
    Some good references:

    - http://forum.notebookreview.com/gam...-overblocks-vbios-afterburner-evga-etc-4.html
    - http://forum.notebookreview.com/gam...ards/723012-gtx-780m-overclocking-tool-5.html

    Seems that you can safely get +200MHz out of the core and +300MHz out of memory clocks, with diminishing returns on the memory side.

    I'm running 150/225 core/mem right now on my 780M via EVGA Precision X (http://www.evga.com/precision/) and will push on from there depending on heat/performance. Always best to take it easy and assume you have a "sub-par" bin.

    Added: Maxing out at 80C at those clocks. Ambient temp is 20C.
     
  23. Tjosansa macrumors regular

    Tjosansa

    Joined:
    Jul 27, 2013
    #23
    But what does it mean in fps in games? Would like to hear a comparison unclocked and clocked..
     
  24. Gherkin macrumors 6502

    Joined:
    Apr 9, 2004
    #24
    I have the 780M w/ 4 GB VRAM. I do a lot of After Effects work.

    would I see any benefits in AE by overclocking my 780m?
     
  25. elithrar macrumors 6502

    elithrar

    Joined:
    May 31, 2007
    #25
    I can't say authoritatively, but I doubt AE maxes out the GPU on a consistent basis. You're also not really able to overclock a card in OS X, either.

    ----------

    It's hard to say quantitatively just yet. I'll need to run some benchmarks (either in-game or artificial), as regular gameplay is way too unpredictable to pull reliable results from.

    A very rough figure would be a roughly 10FPS gain on the top-end in Guild Wars 2, though.
     

Share This Page