Sidebar Sidebar
Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.

6750m extreme overclocking guide

Ended up finding my issue. Although my GPU ran without artifacts up to 883Mhz. Anything over the stock voltage was crashing my GPU. Crysis wasn't crashing rather my GPU was turning off. I am not sure if this is related to running two monitors, although I only run one monitor in windows I am not sure if just having two connected is stuffing up my overclock.
 
shansoft said:
How you turn off the turbo boost? :eek:
Click to expand...

There are 2 options.

1. Set the max cpu to 99% in your advanced power plan settings. I create a special power plan for gaming with this set as I still get great fps but much better heat management.

2. use throttlestop and disable TB in there. You can also use throttlestop to set your own throttling which is more aggressive than intels. This is a bit complicated but you can control the temp at which it lowers the multiplier
 
Wow, I'm really impressed with this. I just set the "basic" overclock and undervolt of 750/950 and .955V and it not only worked great but there were no issues at all. I have to really play test it, but the temps crept up to 85 and then once the fans kicked in down to 79-80c.

This is really great though. The Witcher 2 ran almost good enough with everything set to high with a FPS of around 24. Then after this overclock I get around 31 FPS, which makes everything feel so much smoother.

THANKS FOR THE TIP!
 
Assuming you were to undervolt it to .955V while applying a generous oc of 750/950, then is there any "real" reason NOT to always have OC'd? What's the point of having it revert to stock clocks and voltage if it's technically sipping less power, despite it running at higher clock speeds? Am I missing something here?
 
2hvy4grvty said:
Assuming you were to undervolt it to .955V while applying a generous oc of 750/950, then is there any "real" reason NOT to always have OC'd? What's the point of having it revert to stock clocks and voltage if it's technically sipping less power, despite it running at higher clock speeds? Am I missing something here?
Click to expand...

Well I noticed when I'm OC'd it's always OC'd to the clocks I set (800/900), but at default clocks it will step down to 200 or so when I'm just at desktop doing browsing. This is a heat factor thing I guess and maybe it doesn't use up all the voltage at the underclocked speeds either. I keep it at default when I'm just chillin cuz I feel like it doesn't heat up as much from the higher clocks. But who knows.
 
Well I'm talking more about during non-gaming periods. I know that with a default setups, the 6750m automatically underclocks its GPU when not "in use". Would it still do that if you messed with it?

Theoretically, the 0.955V rating only applies when under full load. We can agree that wattage (the measure for power) consumption is obviously lower when at lower clocks (you can measure this yourself), and assuming resistance stays the same, then a simple P = V^2/R would tell you that voltage is lower. This is true based on intuition anyway.

Basically, my point is, if you applied an undervolt, does that carry over to when the discrete card isn't "in use"? What about if you applied an overclock? My understanding is that when you "tweak" it, it's on with the OC and the undervolt permanently. So even while just idling, the graphics card is still running at full speed, aka drawing more power and creating more heat than if it was left stock, and therefore, allowed to underclock itself.
 
You're referring to "Powerplay", the feature for the card to automatically underclock itself. I assume its better to keep it in this state than a permanent undervolt.

The best way I found out to go about doing this with ATT is to set Overclocking to Automatic when it detects any 3d program "put media players such as VLC in the exclusion list" and set a hotkey which resets to default clocks so powerplay is re-enabled when not gaming.


ahdickter said:
. I pushed it down to .955v and changed my core and mem clocks to 750/950 respectively. BFBC2 increased by 10-15 fps :D
Click to expand...

with .955v you can go all the way up to 795/1000, its perfectly stable for me.
 
Well I understand OC'ing the GPU, but is it necessary to OC the memory to almost 1000 ghz? IIRC, the memory doesn't even have a temp sensor, so you won't get that nice system hang if you DO push it over the limit as you would with the GPU OC. What are the real world performance difference of say 1000 mhz vs 800 mhz memory speeds?
 
Memory does hang if you push it too much, i.e. over 1050.
The performance increase depends on how much a game utilizes the VRAM. Crysis 2 at 1000 ram is 3-4 fps more than 800 whereas Dead Space 2 gives a mere 1 fps improvement.
 
Which vga driver are you guys using? Is it possible to use updated driver from official ati website? Please advise.
 
Necriss said:
If anyone is wondering, 6750m (600 core) is basically a downclocked 6770m (725 core), explains why it overclocks so well.

http://en.wikipedia.org/wiki/Compar...cessing_units#Mobility_Radeon_HD_6xxxM_Series
Click to expand...
With Notebook CPUs it has always been mostly a Temp issue with overclocking.
Mobile parts are cooler chips than desktop chips and with the same cooling they would probably overclock better than standard desktop chips. Yet they are clocked very low by default.
Desktop Redwoods run at 850 Mhz in highest clock configs. I guess with Temps in check pretty much any 6750M should reach those clocks. Some might require more V and would end up running to hot for the cooling system but really they all offer a tremendous headroom.
 
After much testing I have found mine doesn't overclock well... maximum clocks of about 770Mhz, anything over that and Crysis 2 will randomly crash to a black screen with green lines.
 
Macsavvytech said:
After much testing I have found mine doesn't overclock well... maximum clocks of about 770Mhz, anything over that and Crysis 2 will randomly crash to a black screen with green lines.
Click to expand...

Is that using stock volt? How big is your memory clock? What driver version are you using? And, what is the biggest value for your overclocking using stock voltage? Sorry, too many questions asked.
 
Last edited:
ivsetiaw said:
Anyone using vga driver with version >11.1 for 6750m?
Click to expand...

Upgraded to 11.6, slight improvement from 11.2 and ATT still works.

crysis2benchmark.jpg



Deus ex preview build, runs very smoothly. 1680x1050 res high settings.

dxhr5win7exe2.jpg
 
I think it's really nice to see the performance benefits you've gotten.
But I wonder, is it really safe to boost the memory up to 1000?
 
It depends on what your definition of "safe" is.
Stability? Have no problems at 1000.
Hardware deterioration? Unless you're planning to use the MBP for a decade I wouldn't worry about this at all. Stick to undervolt OC which is probably even better for the hardware compared to stock voltage.
 
Necriss, do you use 11.6 ati mobility driver? Is it alright to use that because i found that it shows that my vga is 6600m/6700m series instead and not 6750m anymore...
 
You must log in or register to reply here.
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.
Top Bottom
Back