With ext. monitor high system load by Deferred Procedure Calls (DPC)

Question

After booting my Thinkpad E540 with an external monitor connected, one core is 50% busy with Deferred Procedure Calls (DPC) and it runs constantly at 100% clock speed (2.2 GHz). See picture below.
After unplugging / reconnecting the HDMI cable the system load goes down to almost 0% and the clock to about 40 %, as it should.
It looks like a driver problem.
How to reproduce it:
(1) The Monitor is connected via HDMI, then power on the Thinkpad while shortly opening the Thinkpad.
(2) After logging in, the Task Manager shows 50% load at one core, the Ressource Monitor shows that all the load is consumed by Deferred Procedure Calls and that the clock is constantly at 100 %.
(3) Open the Thinkpad and disconnect the HDMI cable. The load goes down to almost zero and the clock below 50%, as it should be.
(4) Reconnect the HDMI cable and the load stays at almost zero.
Some Details:
Thinkpad E540, i7-4702MQ, 8 GB, screen resolution 1920 x 1080
Monitor HP LP2275w, resolution 1680 x 1050
Win7 64bit SP1, up to date by Windows and ThinkVantage systemupdate
The intel IGP is active (not Geforce 740M).
It does _not_ matter if only the external screen is activated or the internal and externale are expanded or duplicated in the display settings of Windows.
Has someone else the same problem?
Any ideas what I can do?
Here you see it:
Link to picture
Moderator note; picture(s) converted to link(s) About Posting Pictures In The Forums
Solved!
Go to Solution.

Answer 1

Problem solved, with some help (here and here).
Basically, the solution was the installation of a new intel HD 4600 Graphics driver directly from intel.