我的 Toshiba Satellite L850-Y3110 笔记本电脑上安装了 Ubuntu 14.04.2，同时还安装了 Windows 8.1。最近我安装了 AMD Radeon Crimson 15.12 驱动程序 (fglrx-15.302)。我通过转到电源按钮 -> 关于此计算机验证了 Ubuntu 是否检测到了我的显卡。如图所示这里，显示不正常，界面很慢。我有 ATI Radeon HD 7670M 2GB 显卡。
的输出lspci -vnn | grep VGA -A 12是：
01:00.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] Thames [Radeon HD 7500M/7600M Series] [1002:6840] (prog-if 00 [VGA controller])
Subsystem: Toshiba America Info Systems Radeon HD 7670M [1179:fb22]
Flags: bus master, fast devsel, latency 0, IRQ 47
Memory at b0000000 (64-bit, prefetchable) [size=256M]
Memory at c0000000 (64-bit, non-prefetchable) [size=128K]
I/O ports at 3000 [size=256]
Expansion ROM at c0040000 [disabled] [size=128K]
Capabilities: [50] Power Management version 3
Capabilities: [58] Express Legacy Endpoint, MSI 00
Capabilities: [a0] MSI: Enable+ Count=1/1 Maskable- 64bit+
Capabilities: [100] Vendor Specific Information: ID=0001 Rev=1 Len=010 <?>
Capabilities: [150] Advanced Error Reporting
Kernel driver in use: fglrx_pci
怎样才能以可用的方式运行图形驱动程序？