1440p on T400?

I own a Thinkpad T400 with Intel 4500MHD / Mobility Radeon 3470 graphics. The specs for both GPUs state that they support 2560x1440, but the T400 only has a VGA port. I've found conflicting information on this subject, as VGA officially supports up to 2048x1536 @85 Hz, but some people have managed to use it @2560x1440 with a VGA to DVI converter. Is this possible?
If not, is there any way I can use the T400 @1440p?

 

The ThinkPad Advanced dock, 250310U, I believe is compatible with the T400 and has a PCI slot for a low profile GPU. You might get some traction there and you can probably get the Advanced Dock cheap on eBay.

 

Thanks! I may have found something interesting though.... I looked into the maximum bandwidth for VGA, and found that it is ~400MHz. Using this online video bandwidth calculator, I inputted 2048x1536 @85 Hz and the result was ~401MHz, confirming what I found. I then inputted 2560x1440 @60 Hz and, surprisingly, the result was ~331MHz. Does this mean I can just plug in a VGA cable and set a custom resolution?

 

I recommend you to buy an Advanced Mini Dock (sells for a few bucks nowadays). Via the DVI port of this docking station, you can get up to 2560x1600@60Hz.

 

Wow, that's great! Are you 100% sure? I'll search eBay...

 

I am 100% sure. However, keep in mind that you need a Dual-Link DVI-D cable, because it won't work with a Single-Link cable.

 

I already have a Dual Link cable. Thanks so much!!

 

Another addition: in case of your T400 with switchable graphics, the DVI port of the docking station is linked to the ATI GPU, so it has to run all the time when docked. To decrease the likelihood of a failure of the ATI GPU due to thermal problems, you should propably renew the thermal paste on the CPU and apply a new heat conductive pad onto the GPU.

 

You mean to say that if I have only the Intel graphics enabled, and disabled the ATI ones through the BIOS, I'll have to turn them on to use the DVI port? It won't work on the Intel?

 

Yes, you have to turn on the ATI GPU in order to use the DVI port on the Advanced Mini Dock.

 

I've been trying to get switchable graphics to work and just can't get it to work. Is there any way to enable them in Ubuntu or Windows 7?

 

Have a look at this: https://entropicassembly.com/thinkpadgraphics/
Under Windows 7, it is rather easy, you only need the right driver and the Lenovo Power Manager.

 

Thanks, I'll definitely take a look at that!

 

By the right driver, do you mean the 4500MHD driver from Intel's website and the Catalyst Control Center? Or is there something else I'm missing?

 

No, you need the Switchable driver from Lenovo. As far as I remember, you can update the ATI driver later, but you have to keep the Intel driver provided by the Lenovo Switchable Graphics Driver, otherwise it won't work!

 

Thanks a lot, I figured it out and it works flawlessly!