I'm a long time Nvidia user, just replaced with a Sapphire HD Radeon 7850 the other night.  Ever since, my monitor will not go to sleep after 15 minutes according to my Windows power settings.  Looks like Windows stops generating a desktop image, the screen turns black;  but the mouse pointer remains visible and the monitor backlight is still on.  Definitely the Radeon here, as I said it worked perfectly with my old GTX 260.  Any ideas?

Graphics Card
Sapphire HD 7950, no overclocking

AMD Catalyst Driver Version, and Driver History
Catalyst 13.1.  Upgraded from whatever the included CD installed (label says 12.8/12.10, so not sure which it used)

Operating System
Windows 7 Ultimate 64-bit

Issue Details
See above

Motherboard or System Make & Model
MB = Gigabyte GA-Z77X-D3H (user built system)

Power Supply

ThermalTake Smart 750W

Display Device(s) and Connection(s) Used
Gateway FHD2400, connected to Radeon via DVI cable.  Has a built in USB hub, so monitor is also connected to PC via USB;  and a Logitech webcam is plugged into the monitor's USB port.  (The monitor's USB is also used for downloading camera photos and syncing iPods, but those are only connected when in use.)

Applications and Games
N/A.  Issue is with Windows power settings.

CPU Details
CPU = Intel Core i5 3570K OC'ed to 4.4 GHz.  Multi = 11x, vcore = 1.248

Motherboard BIOS Version
American Megatrends, version F15, 8/22/2012

System Memory Type & Amount
G.Skill Ripjaws X, 16 GB (4x4GB)

Additional Hardware
Boot drive = OCZ Vertex 4 SSD, 250GB.  Also has a Western Digital Velociraptor (250GB) and a Western Digital Caviar (1.5 TB).  A 1.5 TB Western Digital external drive is connected via USB for backup.

Two optical drives, an LG Blu-Ray burner and a Philps DVD-RW burner.

Two CPU fans (push-pull), 3 additional case fans.

Additional Details
Norton reports the system is clean.

Edit - I should add that this behavior is not consistent...sometimes the monitor does go to sleep!  But most of the time it does not, I would estimate 4 times out of 5 it does not go to sleep.  I have not been able to discern a pattern.

7850 / 7950 ...?!?!.

Yes , i have the same issue and also the same mainboard. It seems there is an issue with 7950's on intel Z77X chipset mainboards. What can i say : pray for amd to fix things and next time go with Nvidia (they invest much more in QA and don't need 3 driver releases to actually fix something )

Well at least I know I'm not alone, and there at least one common thread in the MB.  What MB BIOS are you on?  I'm on F15, but I don't see anything in the (sparse) description of F16 or F17f that would imply that a BIOS upgrade will help...

I have the v. F16  whch is the latest (non beta) bios release. F17f is BETA (only secure booting option added) but it does not fix the problem. I already reported this problem to Gigabyte  (i have their Z77X mainboard) and also AMD and they will check on it ... yeah right.

You can do the same maybe if they have enough numbers to show they will bother to fix.

Unfortunately it does not happen all the time so it is hard to reproduce.

To be honest i am sick and tired of free QA'ing for companies i gave hard earned money to. It's like i pay them to do quality assurance tests for them. That will not happen again.