Overclocking 5750 (mobility 5850) - Results inside

[Hellhammer]

You know that the mobile 5850 is based on the desktop 5770 which operate on 850 MHz, so technically you should reach 850 MHz no problem.

The question is the cooling.

Desktop 5770 is 108W chip so we are looking at pretty high power consumption and thus more heat if you OC it to 850MHz as 4850M is ~55W and 5850M is 39W. It's achievable if you speed up the fans enough but it isn't very comfortable then. However, the Juniper chip doesn't seem to go much over 900/900/1300 (core/shader/mem, in MHz) before running into issues so 850MHz is max for iMac IMO. In some cases, increasing the clock speeds by only 30MHz or so from the stock speeds caused a lot issues though this may have been fixed with driver or revision update. 750-800MHz seems to be the sweet spot, it's still not too loud but performance increase is noticeable

 

[Snowcake]

Desktop 5770 is 108W chip so we are looking at pretty high power consumption and thus more heat if you OC it to 850MHz as 4850M is ~55W and 5850M is 39W. It's achievable if you speed up the fans enough but it isn't very comfortable then. However, the Juniper chip doesn't seem to go much over 900/900/1300 (core/shader/mem, in MHz) before running into issues so 850MHz is max for iMac IMO. In some cases, increasing the clock speeds by only 30MHz or so from the stock speeds caused a lot issues though this may have been fixed with driver or revision update. 750-800MHz seems to be the sweet spot, it's still not too loud but performance increase is noticeable

Indeed, but just for testing.

With the clockspeed increasing by 30MHz you mean the desktop 5770 or the imac? I think the first one?

 

[Hellhammer]

Indeed, but just for testing.

With the clockspeed increasing by 30MHz you mean the desktop 5770 or the imac? I think the first one?

Testing wise, of course if someone wants to be our guinea pig Yeah, I meant the desktop 5770, it isn't exactly great for OCing but that is not very relevant to iMac discussion because I doubt anyone is going to try 900MHz in iMac, that's 44% faster than the stock clock Just mentioned it if someone is interested how fast that chip can really go

 

[saschke]

Testing wise, of course if someone wants to be our guinea pig Yeah, I meant the desktop 5770, it isn't exactly great for OCing but that is not very relevant to iMac discussion because I doubt anyone is going to try 900MHz in iMac, that's 44% faster than the stock clock Just mentioned it if someone is interested how fast that chip can really go

You mean like some did with the 320M in the MBP13" ???

 

[henrikrox]

I will atleast try 800 core.

For me i draw a line when the imac starts to make more noise then i would like it to do.

And thats about 2700-3000 mark. I dont want to have a imac that looks sexy but sounds like custom built pc with 10 fans.

The test i did with 750 clock i had 2000-2300 rpm. and the temps were just 74 max.

So first im going to check 800 clock with the same fan speed, and from there raise the fan 100 rpm at a time to find my absolute maximum noise level i can live with.

 

[Snowcake]

I will atleast try 800 core.

For me i draw a line when the imac starts to make more noise then i would like it to do.

And thats about 2700-3000 mark. I dont want to have a imac that looks sexy but sounds like custom built pc with 10 fans.

The test i did with 750 clock i had 2000-2300 rpm. and the temps were just 74 max.

So first im going to check 800 clock with the same fan speed, and from there raise the fan 100 rpm at a time to find my absolute maximum noise level i can live with.

Great,

Are you not curious of what your beautiful beast is capable of?
Just for 1 3dmark-vantage benchmark. I think that beast of you has some power in him!

So you dont have to worry about everyday noises because it is just 1 benchmark.

I cant wait when you posting the results of the 800MHz or maybe higher.

 

[henrikrox]

Great,

Are you not curious of what your beautiful beast is capable of?
Just for 1 3dmark-vantage benchmark. I think that beast of you has some power in him!

So you dont have to worry about everyday noises because it is just 1 benchmark.

I cant wait when you posting the results of the 800MHz or maybe higher.

Dunno if i will do vantage as benchmark when i reach 800 speeds, cause i have no way of knowing what the temp is. i like just to a gpu stress test again, then compare it to the two other results i got.

And lastly if the temps doesnt get to high during the stress test, i can do a vantage test, and a 3dmark06 test.


EDIT; 800/1150 test starting now, if you dont hear from me again, you know what happen

 

[henrikrox]

5 min of stress testing the gpu, i noticed artifacts, the temp were only at 66, but there was some artifacts on the donut, so i closed it, so 800/1150 seems to high

 

[Hellhammer]

5 min of stress testing the gpu, i noticed artifacts, the temp were only at 66, but there was some artifacts on the donut, so i closed it, so 800/1150 seems to high

Could be that the mobility versions differs from desktop version somehow, more restricted or something to provide lower TDP. Can you try 775MHz? Or give another try for 800MHz (maybe tomorrow, let the machine cool down overnight)?

 

[Snowcake]

5 min of stress testing the gpu, i noticed artifacts, the temp were only at 66, but there was some artifacts on the donut, so i closed it, so 800/1150 seems to high

Not only the clock is lower, also the voltage is lower than the 5770.

Well, im curious: You could get the voltage higher with some programs on windows. Are you sure enough to do that?

 

[Nutter]

As I understand it overclocking the GPU memory can be problematic, because there's no temperature sensor in the memory itself and thus no way to be sure that it's at a safe temperature. Perhaps you should try 800/1100?

 

[henrikrox]

I just run a 775/1125 test, and it didnt encounter any problems

Fans were running at 3000 rpm now, but it weirds me out how the temps never reached 64 degrees. Maybe because the fans were much higher now, but still. The test lasted 15 min.

I didnt take any screens, but i will test the speeds with vantage / 3d mark 06 later tonight. Now its movie night with the gf. will post later with the 3d mark results. i will try a 800/1125 also.

So 3 tests
stock
775/1125 in vantage / 3dmark 06
800/1125 in vantage / 3dmark 06

 

[Snowcake]

I just run a 775/1125 test, and it didnt encounter any problems

Fans were running at 3000 rpm now, but it weirds me out how the temps never reached 64 degrees. Maybe because the fans were much higher now, but still. The test lasted 15 min.

I didnt take any screens, but i will test the speeds with vantage / 3d mark 06 later tonight. Now its movie night with the gf. will post later with the 3d mark results. i will try a 800/1125 also.

So 3 tests
stock
775/1125 in vantage / 3dmark 06
800/1125 in vantage / 3dmark 06

If you download hwmonitor:

http://www.cpuid.com/softwares/hwmonitor.html

It wil register the max temperature.

 

[henrikrox]

im already using gpu-z to track avg, min and max gpu temp, and im also running speed fan and everest in the background to double check, still it showed the same thing

 

[henrikrox]

So ive did 3dmark 06 right now, i tried 800/1125. During bencmark it freezed then went to desktop, saying it lost contact.

I think its a voltage issue, cause the card wasnt even reaching 60 degrees. Mind, the ambient temp is now at 14 degrees celsius here, and the fans are running what you see on the screenshots below.

Also, i have checked with hwinfo, gpu-z, everest, and speedfan. They never went over 60 degrees on this test. Therefor i think the problem is voltage, also msi afterburner list 800mhz as max, or close to it.

SInce 800/1125, didnt work, i did 775/1125 vs stock clocks. Restults are under.


Things to notice
* There are different fan speeds now, check screenshot to see what they were
* Ambient temp is quite low
* See gpu-z, there is a max, min, avg temp, its running in the background while 3dmark is running. To record the highest temp, which was 57,5 degrees. Thats amazing.
* Dont mind the very low clock / memory speed on gpu-z on stock clock picture. ITs just underclocking itself while not being used.


TEST 1 (stock clock):
3D mark 06 score: 13497
Max temp: 55 C
Fan 1: 2500 rpm
Fan 2: 2500 rpm
Fan 3: 1700 rpm






Test 2 (OC, 775/1125)
3D mark 06 score: 15237
Max temp: 57,5
Fan 1: 2800 rpm
Fan 2: 2800 rpm
Fan 3: 1800 rpm




Almost 2000 more score.

Cryis bencmark tool next, give me suggestion on what to test. 800 should be possible with voltage tweak. I mean, what can the reason be why its faulting? ITs not hitting 60 degree.

 

[Snowcake]

So ive did 3dmark 06 right now, i tried 800/1125. During bencmark it freezed then went to desktop, saying it lost contact.

I think its a voltage issue, cause the card wasnt even reaching 60 degrees. Mind, the ambient temp is now at 14 degrees celsius here, and the fans are running what you see on the screenshots below.

Also, i have checked with hwinfo, gpu-z, everest, and speedfan. They never went over 60 degrees on this test. Therefor i think the problem is voltage, also msi afterburner list 800mhz as max, or close to it.

SInce 800/1125, didnt work, i did 775/1125 vs stock clocks. Restults are under.


Things to notice
* There are different fan speeds now, check screenshot to see what they were
* Ambient temp is quite low
* See gpu-z, there is a max, min, avg temp, its running in the background while 3dmark is running. To record the highest temp, which was 57,5 degrees. Thats amazing.
* Dont mind the very low clock / memory speed on gpu-z on stock clock picture. ITs just underclocking itself while not being used.


TEST 1 (stock clock):
3D mark 06 score: 13497
Max temp: 55 C
Fan 1: 2500 rpm
Fan 2: 2500 rpm
Fan 3: 1700 rpm






Test 2 (OC, 775/1125)
3D mark 06 score: 15237
Max temp: 57,5
Fan 1: 2800 rpm
Fan 2: 2800 rpm
Fan 3: 1800 rpm




Almost 2000 more score.

Cryis bencmark tool next, give me suggestion on what to test. 800 should be possible with voltage tweak. I mean, what can the reason be why its faulting? ITs not hitting 60 degree.

Well, thats great
You could test 3dmark Vantage with the new clocks or the gta IV benchmark

Since the videocard is a mobile version i think that the gpu must be undervolted, so i think that is the problem of the faulting.

You could look at the voltage on the standard 5770, and increase it a bit.
But be careful if you get it too high.

 

[Hellhammer]

Cryis bencmark tool next, give me suggestion on what to test. 800 should be possible with voltage tweak. I mean, what can the reason be why its faulting? ITs not hitting 60 degree.

PSU might be the bottleneck here plus the voltage, it may not be getting enough power. Even though it's based on desktop chip, I'm not sure are there some "hidden" differences making it unstable when OCing enough

 

[Snowcake]

PSU might be the bottleneck here plus the voltage, it may not be getting enough power. Even though it's based on desktop chip, I'm not sure are there some "hidden" differences making it unstable when OCing enough

Well, this PSU has the ability to power a SSD + a harddisk + Usb devices.

It is almost impossible if this PSU is'nt powerful enough.
I think it is still the undervolting of the mobile chip, it has to be.

Does anyone know the power of the PSU in the imac 27"?

 

[Hellhammer]

Well, this PSU has the ability to power a SSD + a harddisk + Usb devices.

It is almost impossible if this PSU is'nt powerful enough.
I think it is still the undervolting of the mobile chip, it has to be.

Does anyone know the power of the PSU in the imac 27"?

IIRC it's 310W. The issue isn't the power of it but how much power is provided to the GPU. I wouldn't be surprised if it was something like 75W (single PCIe power cord) but that's just a guess. It was just an idea that came to my mind but it could be the voltage or something else

 

[saschke]

I've hit a wall, too. The graphics adapter reset itself after trying MSI
Kombustor for half a minute with the following settings:

Core Clock: 781 Mhz
Memory Clock: 1133 Mhz

Fan speeds at: 1800 1400 1400

ImageShack

With the same fan speeds, I've managed to get the clocks up as high as:

Core Clock: 768 Mhz
Memory Clock: 1102 Mhz

Without ever reaching 80°C in a 360 second test - see the screenshot for comparison.

ImageShack

----

Note that if you set the fan speed with MacFan, they are still valid after a
reboot into OS X - put the Mac to sleep once to reset them to stock speeds
(1000, 1000, 1000). Will test some more now!

 

[henrikrox]

I've hit a wall, too. The graphics adapter reset itself after trying MSI
Kombustor for half a minute with the following settings:

Core Clock: 781 Mhz
Memory Clock: 1133 Mhz

Fan speeds at: 1800 1400 1400

ImageShack

With the same fan speeds, I've managed to get the clocks up as high as:

Core Clock: 768 Mhz
Memory Clock: 1102 Mhz

Without ever reaching 80°C in a 360 second test - see the screenshot for comparison.

ImageShack

----

Note that if you set the fan speed with MacFan, they are still valid after a
reboot into OS X - put the Mac to sleep once to reset them to stock speeds
(1000, 1000, 1000). Will test some more now!

Nice, seems 775, 1125 or around there is max, without figuring whats holding it back.

Whats your ambient temp?

I just think its weird my temps are so freakishly low, allthough i usually run them at 2000 2000 1600 or 2200 2200 1600

edit, doing a test now with 1800 1400 1400 that you used with kumbustor direct3d 11

 

[Snowcake]

IIRC it's 310W. The issue isn't the power of it but how much power is provided to the GPU. I wouldn't be surprised if it was something like 75W (single PCIe power cord) but that's just a guess. It was just an idea that came to my mind but it could be the voltage or something else

That is not much Only 310?

Wel if it is a single PCIe cord of 75W, No problem. The 5850 mobile require 39W and the 5870 mobile (700MHz) require 50W.

But where do you get that info?

Can someone do a intelburntest? To test if the CPU is stable? (Im a little worried with that little PSU power)
Settings: 50 Passes or more? (Choose: Maximum Memory)
Download link below.

http://www.softpedia.com/get/System/Benchmarks/IntelBurnTest.shtml

 

[Snowcake]

Nice, seems 775, 1125 or around there is max, without figuring whats holding it back.

Whats your ambient temp?

I just think its weird my temps are so freakishly low, allthough i usually run them at 2000 2000 1600 or 2200 2200 1600

What do you guys think? Is it Furmark stable?

 

[Hellhammer]

That is not much Only 310?

Wel if it is a single PCIe cord of 75W, No problem. The 5850 mobile require 39W and the 5870 mobile (700MHz) require 50W.

But where do you get that info?

iFixit said the previous gen had 310W, see the step 12. On the other hand, desktop 5770 is 850MHz and 108W so 800MHz could easily suck around 80W. I don't know how the GPU is powered, is it over PCIe or is it an own cable but I wouldn't be surprised if it was limited to e.g. 75W because that can provide the 39W what stock 5850 needs (and ~55W what 4850 needs). That's just a theory and one option

 

[saschke]

Whats your ambient temp?

It's pretty cozy - summer is heating everything up here in Germany - around 24°c. I've put a shortcut to MacFanx64 with 1800 1800 1600 onto my desktop and into autostart for setting the fans at startup, but somehow another one with 1000 1100 1000 does not seem to be able to reset the temps - the error I'm getting: "Unable to read key **** from SMC." -- any clues?