T420 and T520 use QM67 and from what I know, intel will not release an update firmware to support Ivy Bridge.

Technically speaking, there is no reason why Ivy Bridge shouldn't work on a Sandy Bridge laptop. They are essentially the same chip.

They do use the same socket, so nothing to get in the way there. I think you should try it. Here's one:
http://www.ebay.com/itm/INTEL-i7-3520M- ... 801wt_1344

The ebay seller says in the auction description "It will NEVER work with 67 chipsets"

I guess it all comes down to whether or not Lenovo has support for it in the latest BIOS update.

Intel has said the mobile CPUs are not upgradeable. Buying one would be a waste of money. The performance bump for Ivy Bridge is very modest and probably not worth the trouble. The GPU is where Ivy Bridge shines and that's not upgradeable at all.

Isn't the GPU on-die?

Eh? The GPU comes with the processor so if you replace a Sandy Bridge with an Ivy Bridge, you upgrade the GPU from HD3000 to HD4000 (my main reason to upgrade). Now, that this is actually possible (the missing software part mostly), I'm not sure.

And yes, I agree, I wouldn't burn my money trying right now as it just came out. But later down the road be sure that I will. And by the way, since my only interest is the GPU, I'd rather pick a lower end model. Though it seems that i7 models have faster GPU (a few extra MHz in turbo)...

I know for a fact, though, that in the Core 2 Duo days a Penryn CPU could be dropped in any Merom motherboard. It displayed an error but it worked. I wouldn't be surprised if it's the same with Ivy Bridge.

some news or progress ? THX.

Unless someone here is willing to donate one for testing, I'm pretty sure we'll have to wait some more time until prices drop and it makes sense to risk failure to upgrade. The most likely outcome is that it will not work and burning $100 or more to get a chip you don't be able to use doesn't make much sense right now.

You may want to check the Sandy Bridge chipset QM67 and the Ivy Bridge chipset QM77.