Switchable graphics and GM45

As we all know, Lenovo has some models with this technology, called switchable graphics. This is thanks to some implementations on software and the existence of both an IGP and a GPU inside the laptop.

So, now I wonder something. As the Lenovo IdeaPad U300 has switchable graphics between the GMA4500MHD and the ATi Radeon 3450HD using the Intel Chipset Mobile Intel GM45 Express Chipset (Graphics Memory Controller Hub) plus the ICH9M I/O Controller Hub. I guess, since same hardware is used, the T400, T500, W500 and Sony VAIO Z use the exact same chipset, to allow switching.

I guess most laptops use this Chipset GM45 and the ICH9M, right?
For example, the Sager NP7350 Built on Clevo M7350T uses the exact same Chipset, but only has IGP.

Well, my question is, if another laptop uses the same GM45+ICH9M but has a GPU, can you enable it to work as switchable? Since GM45 is the chipset that supports the GMA4500MHD, if you place a GPU as well, can you convert the IGP-based laptop into a fully switchable graphic based laptop?

For example, the HP DV3t can be configured with either a GMA4500MHD or a GT105M, right? Well, if it can use the GMA4500MHD, it has the GM45+ICH9M if not mistaken, what if you place inside a GPU? Will the switchable be possible?

Basically I am asking if you can convert an IGP laptop into a GPU laptop, by using the same Chipset other laptops with switchable graphics have. If this is possible, then we all can imagine what would happen...right?

 

No, you cannot convert an IGP laptop into a GPU laptop. I believe it's a lot more complex than what you have decribed. There have been a couple of discussions in the past on NBR regarding this and it was concluded that there are certain hardware changes that were done to make switchable graphics possible. Normally in a motherboard with an IGP, when you connect a discrete GPU, it disables the IGP. It requires additional hardware to be able to switch GPUs on the fly. In notebooks w/ IGP, I think manufacturers usually disable the slot so that you cannot install a discrete GPU into it or have prevented support via hardware or BIOS/software.

 

Wait...let me see if I get this correctly.

Manufacturers disable the GPU slot when the IGP is present, right?
So you can not place a GPU, and if you could, the "switchable" is not possible because of missing hardware?

Ok, how about this case. You have a GPU-based laptop with GM45+ICH9M, lets say the DV3t again, it can carry a GT105M.
Ok, you get that version, but the chipset is still GM45, can you enable the IGP? Or is it "blocked"?
If it is somehow blocked (due to BIOS/software) it is still present on the MoBo, right? So if you can go around these "walls" you could enable it...

 

I thought they would usually pair the PM45 chipset with models with a dedicated GPU.

 

Yeah, PM45 is for dedicated graphics, GM45 is with integrated.

 

And how can the U330 use the GM45 while it has a GPU as well?

 

Special Drivers plus special hardware.

 

is that the only solution? special x+special Y?
the a GPU-based laptop uses a PM45 instead of the GM45.

One question comes to my head, if you get an Inspiron for example, it uses GMA4500MHD, therefore GM45, but if you upgrade to an ATi 4330HD, then the MoBo is different?

 

Yes - the motherboard is physically different in order to accomodate the GPU and the different chipset.

 

what are the differences between the GM45 and the PM45, apart from the obvious ability to use the GMA4500MHD in the first and GPU in the second?

Is there any actual difference in this?

 

There are no other differences. From the chipset specs (via Intel.com), the GPU consumes 5W, as the GM45 consumes 14.5W and the PM45 consumes 9.5W (7W for the actual chipset, 2.5W for ICH9 controller). Most companies will use the PM45 chipset for discrete GPUs as the motherboard is slightly cheaper than the GM45 chipset. Only a few companies (Lenovo, Alienware, Sony) have developed special notebooks with discrete graphics and the GM45 chipset.

 

That is too bad too hear/read.

If you could enable switchable on every laptop, it would give a huge boost on battery life. And make some other laptops much more competitive.

Is it that difficult to enable these special chipset-MoBo combo? What is so "special" about the GM45, if it has the GPU slot there, then there is no problem, right?

Because I am quite sure that most people around here would love to have switchable graphics on their laptops, so they can get a lot more battery life...

 

I agree, I wish more notebooks took advantage of switchable graphics. Unfortunately, most notebook GM45 motherboard manufacturers disable the PCIe slot for discrete GPU access or leave it out completely to save space.

 

The GM45 does not have a GPU slot for a discrete GPU. If it has a slot at all, the GMA4500MHD occupies it, and there physically isn't any other slot/space avaliable for another GPU (discrete.) What Lenovo, Sony, etc did was make a special motherboard that can carry 2 GPU's (one is the Intel GMA and the other, a discrete GPU.) Ordinary laptops don't have the space for you to add a discrete GPU next to an already present intel GMA. If you see laptops that offer a GPU choice when you build them (example: the dv3t you were talking about) the version with the Intel GMA has a completely different motherboard/heat assembly than the version with the discrete GPU.

 

PM45 has no graphics on the chip, its not disabled it just does not exist. It does support lane splitting for crossfire.

 

That is correct, if you thought I said otherwise than I didn't mean it that way.

 

Huh? PM45 supports crossfire? Then it has more than on slot?

 

No, it still uses one slot but companies that have 2 GPUs basically split the PCIe lanes. I believe they tweak their motherboard so that it can physically support two.

 

Just because a chipset supports a feature does not mean the board does. The G45 can't have its lanes split though.

The pins to the G45 would have to be routed to the display ports etc so its easier to design with just the dedicated card and P45 if you are going dedicated at all.

 

Sorry Meaker, but I did not fully understand that...