Bootcamp Windows 2560x1440 external monitor problem

Hello.I bought macbook pro 13 (late 2013) and connected it to my external monitor via miniDP to DP adaptor.Installed windows 8.1, but maximum available resolution is 2048x1152 (monitor supports 2560x1440), than installed Windows 7 and problem is the same.Have last drivers.

In Mac os everything is perfect.
Graphic card is Intel iris 5100.

Please help.

If you're not getting the native resolution from your external monitor, it has to be a graphics driver problem. The Iris Pro GPU is new and there may not be drivers available that result in the maximum resolution possible (native resolution). You can try going directly to the Intel Web Site and see if they have the latest Windows drivers for the Iris Pro.

Hmm, but if i disconnect adapter i can get 2560x1440 on macbook internal screen.I thought about the adapter problem, but in mac everything is ok.Will try reinstall drivers one more time.