Radeon HD6750/70 Overclocking [Bootcamp]

Discussion in 'iMac' started by Kerel, Jun 25, 2011.

  1. Kerel macrumors member

    May 19, 2011
    Weimar Germany
    There already is a thread about Imac 2011 overclocking but it focusses more on the high end HD6970m.
    This thread is purely for HD6750 and HD6770 users.

    I´m a base 21" 2011 imac owner and this is my first mac. I used to be a pc builder/overclocker and gamer and i just want to know how much i can tweak my imac for gaming.

    The base frequencies of the HD6750m are 600/800Mhz and i got mine up to 800/1000Mhz respectively using the Sapphire TriXX tool. All on stock voltage with max temp lower then 80C and without increasing any fanspeeds.

    This represents a 33% overclock for the shaders and a 25% increase of memory frequency and should be noticable in gaming. It is also higher than the HD6770 stock speeds which i still don´t know the exact memory speed of? Is it 800 or 900Mhz not 1600 found on the net.

    Can anyone post the exact clockspeed? Preferably a Sapphire Trixx read out?

    I could not increase the shader speed anymore with the Sapphire TriXX tool but i have a feeling that there was more possible. Somewhere between 850 and 900 with a slight increase in core voltage. You can only increase the voltage by the TriXX tool with 0.05 volt which is around 5% and should be totaly safe.

    Would be interresting if you could increase the shader speed for the HD6770 above 800 because of its higher base clockspeed of 725Mhz????
    Can anyone verify this?????

    Increasing the memory speed to 1050 caused for lockups (i hoped they would have gone all the way up to 1100 as the HD6970 does). I haven´t tried anything in between 1000 and 1050 because i don´t think it would make much of a difference.

    The memory chips used are hynix H5GQ1H24AFR T2L chips (i know this from the ifixit teardown) rated at 1.25Ghz @ 1.5v and 800Mhz @ 1.35v. It would be very interesting what voltage Apple is using, because this would probably hugely effect the overclocking possibilities and might explain why i could not reach 1050 Mhz.
  2. A Macbook Pro macrumors 6502

    Aug 22, 2009
    Welcome to Mac :)

    If I was you I wouldn't be posting such advanced gaming and over clocking stuff here. As you can see you won't get many replies. You'd be better off on a PC forum (even though you'd get ridiculed for owning a Mac).

    I own a high-end iMac with the 6970M and gaming is great. I overclock with TRIXX to 900/1100 and get great FPS. There's a thread on iMac 2011 overclocking a page or two back, it has some great info.
  3. Kerel thread starter macrumors member

    May 19, 2011
    Weimar Germany
    Thanks for you´re reply and i won´t be posting any in depht overclocking artikels any more.
  4. kelub macrumors regular

    Jun 15, 2010
    Hey I'm a gamer and a Mac convert too (I also have the 21" w/ 6750m), and I am grateful to find your thread. As I get older my gaming becomes secondary to my other computer needs, but it's still nice to find nuggets of good info about gaming specific stuff. Don't get discouraged, if your info helps even 1-2 people it was worth posting.
  5. chris1184 macrumors regular

    Apr 26, 2011
    as a first time iMac owner (21.5 inch HD6770M 2.7 i5) and fellow gamer this is very interesting to me...i have never overclocked any machine i own but I'd like to think of myself as pretty computer saavy. How hard would it be for me to overclock my gpu? and what tools do I need....also what are the chances i can F up my brand new iMac ? (does it void warranty?)

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