Трудно объяснить словами, и я не понимаю куда капать вообще
Kubuntu 14.04
00:02.0 VGA compatible controller: Intel Corporation Xeon E3-1200 v2/3rd Gen Core processor Graphics Controller (rev 09) (prog-if 00 [VGA controller])
Subsystem: Gigabyte Technology Co., Ltd Device d000
Flags: bus master, fast devsel, latency 0, IRQ 44
Memory at f7800000 (64-bit, non-prefetchable) [size=4M]
Memory at e0000000 (64-bit, prefetchable) [size=256M]
I/O ports at f000 [size=64]
Expansion ROM at <unassigned> [disabled]
Capabilities: [90] MSI: Enable+ Count=1/1 Maskable- 64bit-
Capabilities: [d0] Power Management version 2
Capabilities: [a4] PCI Advanced Features
Kernel driver in use: i915

Xorg.0.log без ошибок
в dmesg ругулся на conflicting fb hw usage inteldrmfb vs VESA VGA - removing generic driver , но это не то
ЧТо ещё можно посмотреть?