Note: I've seen this question quite a lot, but in all the cases I could find with answers, the answer was either "I don't know" or "use nvidia-settings (which is irrelevant to me)."

I'm using Intel Sandybridge Desktop graphics, with a P8H61-M LE motherboard. How do I get Ubuntu to detect my second monitor?

Clicking "Detect Displays" here doesn't do anything.

Here's some system info:

$ lspci | grep VGA
00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09)

$ uname -a
Linux clyde 3.5.0-13-generic #13-Ubuntu SMP Tue Aug 28 08:31:47 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux

$ hardinfo
[copied from the UI]
-Display-
Resolution              : 1920x1080 pixels
Vendor                  : The X.Org Foundation
Version                 : 1.12.3
-Monitors-
Monitor 0               : 1920x1080 pixels
-Extensions-
BIG-REQUESTS
Composite
DAMAGE
DOUBLE-BUFFER
DPMS
DRI2
GLX
Generic Event Extension
MIT-SCREEN-SAVER
MIT-SHM
RANDR
RECORD
RENDER
SECURITY
SGI-GLX
SHAPE
SYNC
X-Resource
XC-MISC
XFIXES
XFree86-DGA
XFree86-VidModeExtension
XINERAMA
XInputExtension
XKEYBOARD
XTEST
XVideo
-OpenGL-
Vendor                  : Intel Open Source Technology Center
Renderer                : Mesa DRI Intel(R) Sandybridge Desktop 
Version                 : 3.0 Mesa 8.1-devel
Direct Rendering        : Yes

I've tried upgrading everything from ppa:xorg-edgers/ppa and ppa:glasen/intel-driver. I've also installed various tools I've found in other threads (e.g. hardinfo) but they weren't really helpful to me as I don't know what to make of the data. How do I get Ubuntu to detect my second monitor?