Better performance with Iris Pro graphics than 750m? (rMBP 15")

anthonya1999 · Aug 22, 2014

I just bought a retina macbook pro, and I got the model with the 750m graphics card. When I turned off the option that said automatic graphics switching in the energy saver section of system preferences, it gave me a message that said the computer would always use high performance graphics. However, I noticed some lag when I started using it, especially with animations. I went to the apple store, and told them the problem. They said that this was because since the NVIDIA graphics card has 2GB of memory, that acted as my RAM, and the 16GB was not actually doing anything/being used, and with the switch turned on, it actually uses BOTH GPU's (or at least they work together somehow). So he told me to turn the switch back on.

I feel like since the computer told me that it would be "high performance", the guy at the store was contradicting what the computer was telling me...does this make sense? Was the guy at the apple store telling me to turn it back on because that's the default or something?

Thanks.

remingtonjd · Aug 22, 2014

anthonya1999 said:
I just bought a retina macbook pro, and I got the model with the 750m graphics card. When I turned off the option that said automatic graphics switching in the energy saver section of system preferences, it gave me a message that said the computer would always use high performance graphics. However, I noticed some lag when I started using it, especially with animations. I went to the apple store, and told them the problem. They said that this was because since the NVIDIA graphics card has 2GB of memory, that acted as my RAM, and the 16GB was not actually doing anything/being used, and with the switch turned on, it actually uses BOTH GPU's (or at least they work together somehow). So he told me to turn the switch back on.

I feel like since the computer told me that it would be "high performance", the guy at the store was contradicting what the computer was telling me...does this make sense? Was the guy at the apple store telling me to turn it back on because that's the default or something?

Thanks.

Interesting... I have heard of these issues and did not investigate until my rMBP arrived today! (Proud owner!!). I would like to know the answer to this as well as I frequently game on my Macs and was hoping to take advantage of my brand new 750M.

blooperz · Aug 22, 2014

anthonya1999 said:
They said that this was because since the NVIDIA graphics card has 2GB of memory, that acted as my RAM, and the 16GB was not actually doing anything/being used, and with the switch turned on, it actually uses BOTH GPU's (or at least they work together somehow). So he told me to turn the switch back on.

sounds pretty wrong to me...I'm no expert but that sounds like a load of **** from someone that didn't have a real explanation....I'd get a 2nd opinion if I were you...

Tea-Aholic · Aug 23, 2014

The guy is talking complete nonsense.

The 16GB of RAM is always available to the system.

With "Automatic graphics switching", the Intel Iris Pro will be utilised normally with the GT 750M coming on automatically when programs require more GPU power.

With it unchecked, only the higher performance 750M will be used.

The GPUs are never working at the same time, either one or the other.

FuNGi · Aug 23, 2014

Tea-Aholic said:
The guy is talking complete nonsense.

The 16GB of RAM is always available to the system.

With "Automatic graphics switching", the Intel Iris Pro will be utilised normally with the GT 750M coming on automatically when programs require more GPU power.

With it unchecked, only the higher performance 750M will be used.

The GPUs are never working at the same time, either one or the other.

Some applications do use both GPU's but they have to be coded to so (FinalCutPro, Adobe Premier Pro) but that does not appear to be what was causing the issues the OP was having. The Apple Genius was making up a story on the spot. OP, download gfxCardStatus and you'll see which applications trigger the NVIDIA card not all do and you'll be able to more passively assess if you have a glitchy system or it was just a one-off event. I've had no issues related to whether I'm using the iGPU or the NVIDIA GPU on my late 2013 rMBP.

Celedral · Aug 23, 2014

Wow, these specialist are getting more and more incompetent. They can say anything and people will believe them since they wear an apple logo. I remember once a specialist was telling a customer all the laptops were QUADCORE when clearly they were dual core i7 (no QC at that time). I was furious, but didn't want to butt in at that time.

merrickdrfc · Aug 23, 2014

Not sure what the OP is experiencing, I have zero UI/system lag running either the 750M or Iris Pro GPU - Mid 2014 MBP.

But yeah you can't really trust what they come out with a lot of the time, I remember over hearing a conversation from a specialist informing someone that the 'MacBook Air can be so fast due to the fact it doesn't need a processor, it's a completely new system architecture' - back in 2010, not sure the guy would have cared either way but still not really very professional.

Tea-Aholic · Aug 23, 2014

FuNGi said:
Some applications do use both GPU's but they have to be coded to so (FinalCutPro, Adobe Premier Pro)

There is NO application that uses both GPUs. Final Cut only uses the discrete card.

FuNGi · Aug 24, 2014

Tea-Aholic said:
There is NO application that uses both GPUs. Final Cut only uses the discrete card.

I guess I was operating under old information regarding openCL providing the ability to say, use both the old 9400 and 9600 graphics chips in older macs. What I said appears only to pertain to the dual GPU's in mac pros. Apparently, the Intel GPU in the rMBP is deactivated once the GPU kicks in. I'm curious if the new iMacs contain CPU's with our without a iGPU?

leman · Aug 24, 2014

FuNGi said:
I guess I was operating under old information regarding openCL providing the ability to say, use both the old 9400 and 9600 graphics chips in older macs. What I said appears only to pertain to the dual GPU's in mac pros. Apparently, the Intel GPU in the rMBP is deactivated once the GPU kicks in. I'm curious if the new iMacs contain CPU's with our without a iGPU?

Tea-Aholic said:
There is NO application that uses both GPUs. Final Cut only uses the discrete card.

OS X allows any number of available GPUs to be utilised at the same time, no matter which GPU is currently used to drive the display. There are APIs to do that. Your application will need to request it explicitly though.

Tea-Aholic · Aug 27, 2014

FuNGi said:
I guess I was operating under old information regarding openCL providing the ability to say, use both the old 9400 and 9600 graphics chips in older macs. What I said appears only to pertain to the dual GPU's in mac pros. Apparently, the Intel GPU in the rMBP is deactivated once the GPU kicks in. I'm curious if the new iMacs contain CPU's with our without a iGPU?

The entry level iMacs don't have discreet graphics so they just onboard Intel Graphics. The upper end ones have discrete NVIDIA graphics. There is no GPU switching on iMacs, even with the discrete configurations because there is no power constrains like on notebook computers.

leman said:
OS X allows any number of available GPUs to be utilised at the same time, no matter which GPU is currently used to drive the display. There are APIs to do that. Your application will need to request it explicitly though.

Please stop thinking that the MacBook Pro can use both GPUs at the same time. OS X being able to do so doesn't mean the MBP can. Apple engineered to have either Integrated or Discrete at a single time, not both.

leman · Aug 27, 2014

Tea-Aholic said:
Please stop thinking that the MacBook Pro can use both GPUs at the same time. OS X being able to do so doesn't mean the MBP can. Apple engineered to have either Integrated or Discrete at a single time, not both.

Sorry, but you have no idea what you are talking about. I have actually written applications which use both GPUs at the same time. Works like a charm.

You are confusing the notion of the 'online' GPU (the one that is currently used to drive a display) and that of 'used' GPU (the one your application uses for this or other purpose). You can still use a offline GPU to draw to memory buffers and than copy that buffer to your online GPU.

Please refer to Apple developer documentation for more information.

P.S. I can also point you to this thread, where this is discussed in more details (with a demo): https://forums.macrumors.com/threads/1688619/

Tea-Aholic · Aug 28, 2014

leman said:
Sorry, but you have no idea what you are talking about. I have actually written applications which use both GPUs at the same time. Works like a charm.

As much as your experiment went, I don't see that the current setup can be worthy. There are no applications that do this, reason being it is impractical due to the setup.

TechZeke · Aug 28, 2014

This thread is as confusing as the Genius at the Apple store telling the OP that his system wasn't using system RAM because the dGPU was enabled.

0940732 · Aug 28, 2014

I believe that OS X basic animation are designed for intel integrated graphics since every mac has this graphics and dGPU is reserved just for apps with great demand on GPU

leman · Aug 28, 2014

Tea-Aholic said:
As much as your experiment went, I don't see that the current setup can be worthy. There are no applications that do this, reason being it is impractical due to the setup.

So now that you have been proven wrong, you try to substitute the topic

To refresh your memory, we were talking about whether its possible, not whether its worthy.

That aside, I agree that the usefulness of such setup is questionable in most cases. There is an overhead in synchronising the GPUs, so there are only few situation which I can envision, that would benefit from this technique. One notable exception are multi-GPU computers like the Mac Pro, where the potential gain is higher than the overhead. E.g., one could easily program an Alternate Frame Renderer using this technique.

Tea-Aholic · Aug 29, 2014

leman said:
So now that you have been proven wrong, you try to substitute the topic To refresh your memory, we were talking about whether its possible, not whether its worthy.

That aside, I agree that the usefulness of such setup is questionable in most cases. There is an overhead in synchronising the GPUs, so there are only few situation which I can envision, that would benefit from this technique. One notable exception are multi-GPU computers like the Mac Pro, where the potential gain is higher than the overhead. E.g., one could easily program an Alternate Frame Renderer using this technique.

Well, practicality is important, so if it's not really practical to do then why bother. If you could use both GPUs at the same time to boost performance significantly Apple would have done that.

The Mac Pros 2X GPU setup is designed to be high performance, the ones on the notebooks aren't. Even my Sony VAIO had 2 GPUs but aren't able to use both at the same time.

SarcasticJoe · Aug 29, 2014

That really doesn't sound right... Partly because the 750M is about twice as fast as the Iris Pro and partly because the Iris Pro is limited to a maximum 1,5GB chunk of the system RAM. Not only does the 750M have more RAM (2GB as previously mentioned), it has faster RAM of a type called GDDR5.

The real reason here is probably that you're using software that hasn't been tested on the 750M and thus relies purely on the CPU to avoid any unexpected problems. The new Mac Pro had a similar problem with Adobe Premiere where it actually ran slower than on some higher end old machines because on the old machines it utilized the GPU and on the new machines it ran purely on the CPU.

You really shouldn't go to retail to ask anything but basic stuff because they're pretty much clueless when it comes to anything slightly more technical. They don't teach them any of the more technical stuff, they're there to sell computers to old ladies and other semi-clueless people who can't look up the facts on their own.

MagicBoy · Aug 29, 2014

The rMBP can utilise both GPUs simultaneously for OpenCL, but not as a video display device.

Don't believe me? Try the Luxmark benchmark app.

leman · Aug 29, 2014

MagicBoy said:
The rMBP can utilise both GPUs simultaneously for OpenCL, but not as a video display device.

I gave a link above to where I showcase a program that uses both the iGPU and the dGPU for rendering to different portions of a window at the same time. Yes, it is not of much practical importance, but it is possible.

Better performance with Iris Pro graphics than 750m? (rMBP 15")

macrumors member

macrumors newbie

macrumors 6502

macrumors 6502

macrumors 65816

macrumors 6502

macrumors 6502

macrumors 6502

macrumors 65816

macrumors Core

macrumors 6502

macrumors Core

macrumors 6502

macrumors 68020

Cancelled

macrumors Core

macrumors 6502

macrumors 6502a

macrumors 68040

macrumors Core

Our Staff