Gadgets : Acer Extensa E420 Desktop

Acer Extensa E420 Desktop AMD 1640B Athlon

Good Points :

• A steal at less than £150
• 64 bit Processor
• HDMI connector
• High Quality Audio Card
• Motherboard can take up to 8 gigabytes of RAM
• 4 USB ports plus audio input/output on the front of the base unit
• Gigabit Network Card
• 160 Gigabtye SATA Hard Disk
• Very, very quiet
  

Bad Points :

• Single Core Processor
• ATI Graphic Driver provided by AMD/ATI and approved by Ubuntu Development Team can be unstable
  
• Memory is very specific, ie; you cannot use anything faster than the PC2 5300 667Mhz. I tried 800Mhz and it caused massive instability, but I also found that PC2 4200 444Mhz will actually work safely.
• BIOS does not have an option to move the AGP aperture, this can cause problems, if you install 4 gigabytes or more of RAM as this aperture is placed in the high memory and from my research, I found that both Microsoft Windows and Linux attempt to mark the area as reserved. Linux uses 64 megabytes and the Windows system will reserve around 1 gigabyte of memory. Unfortunately, this reservation can be overwritten causing instability. See following example from my kernel log;

Jun 8 16:40:36 ub02 kernel: [ 0.000000] Checking aperture...
Jun 8 16:40:36 ub02 kernel: [ 0.000000] No AGP bridge found
Jun 8 16:40:36 ub02 kernel: [ 0.000000] Node 0: aperture @ 2832000000 size 32 MB
Jun 8 16:40:36 ub02 kernel: [ 0.000000] Aperture beyond 4GB. Ignoring.
Jun 8 16:40:36 ub02 kernel: [ 0.000000] Your BIOS doesn't leave a aperture memory hole
Jun 8 16:40:36 ub02 kernel: [ 0.000000] Please enable the IOMMU option in the BIOS setup
Jun 8 16:40:36 ub02 kernel: [ 0.000000] This costs you 64 MB of RAM
Jun 8 16:40:36 ub02 kernel: [ 0.000000] Mapping aperture over 65536 KB of RAM @ 20000000

Conclusion; As a long time Ubuntu and Linux user, this computer is steal and runs like a dream in full 64 bit, but the 4 gigabyte AGP aperture is an issue because of the integrated video card and reservation being overwritten. I was forced to reduce my memory to allow the BIOS to put the aperture in lower memory, but for a Linux user that is probably less of an issue than for a Microsoft user, where memory is often a premium.

Further Reading:
http://www.acer.co.uk
http://www.ebuyer.co.uk