With kernel 3.12 I'm experiencing a complete freeze of gnome. Also with new 3.12.6.
I just started with fedora 19, after the kernel upgrade gnome freeze just after the login. I have found that application cairo-dock (without opengl enabled) causes the freeze. Then also other applications.
I have performed a fresh installation of fedora 20 and I'm experiencing random gnome freeze.
The only one I can reproduce always is simply launching gnome-control-center.

Everything  is working fine with kernel 3.11.10-301.fc20.x86_64
Logs are useless, because simply fedora stop to write logs. I can only perform an hard reset when gnome freeze. Quite annoying...

Version-Release number of selected component (if applicable):
fedora 20 on a thinkpad lenovo T430.
~]# lspci
00:00.0 Host bridge: Intel Corporation 3rd Gen Core processor DRAM Controller (rev 09)
00:01.0 PCI bridge: Intel Corporation Xeon E3-1200 v2/3rd Gen Core processor PCI Express Root Port (rev 09)
00:02.0 VGA compatible controller: Intel Corporation 3rd Gen Core processor Graphics Controller (rev 09)
00:14.0 USB controller: Intel Corporation 7 Series/C210 Series Chipset Family USB xHCI Host Controller (rev 04)
00:16.0 Communication controller: Intel Corporation 7 Series/C210 Series Chipset Family MEI Controller #1 (rev 04)
00:16.3 Serial controller: Intel Corporation 7 Series/C210 Series Chipset Family KT Controller (rev 04)
00:19.0 Ethernet controller: Intel Corporation 82579LM Gigabit Network Connection (rev 04)
00:1a.0 USB controller: Intel Corporation 7 Series/C210 Series Chipset Family USB Enhanced Host Controller #2 (rev 04)
00:1b.0 Audio device: Intel Corporation 7 Series/C210 Series Chipset Family High Definition Audio Controller (rev 04)
00:1c.0 PCI bridge: Intel Corporation 7 Series/C210 Series Chipset Family PCI Express Root Port 1 (rev c4)
00:1c.1 PCI bridge: Intel Corporation 7 Series/C210 Series Chipset Family PCI Express Root Port 2 (rev c4)
00:1c.2 PCI bridge: Intel Corporation 7 Series/C210 Series Chipset Family PCI Express Root Port 3 (rev c4)
00:1d.0 USB controller: Intel Corporation 7 Series/C210 Series Chipset Family USB Enhanced Host Controller #1 (rev 04)
00:1f.0 ISA bridge: Intel Corporation QM77 Express Chipset LPC Controller (rev 04)
00:1f.2 SATA controller: Intel Corporation 7 Series Chipset Family 6-port SATA Controller [AHCI mode] (rev 04)
00:1f.3 SMBus: Intel Corporation 7 Series/C210 Series Chipset Family SMBus Controller (rev 04)
01:00.0 VGA compatible controller: NVIDIA Corporation GF108M [NVS 5400M] (rev a1)
02:00.0 System peripheral: Ricoh Co Ltd PCIe SDXC/MMC Host Controller (rev 07)
03:00.0 Network controller: Intel Corporation Centrino Advanced-N 6205 [Taylor Peak] (rev 34)



How reproducible: always starting gnome-control-center



Additional info:
I'm available to perform some tests and for any further information you need.
many thanks
Emanuele