If you can, try reducing the amount of installed RAM to a single stick and attempt the installation again.

If you have any non-essential devices attached to the system, try disconnecting them.

Which method are you using to install Windows 8, DVD/Thumb drive or Web Installer.

If you are using Web Installer, try using the DVD/Thumb drive instead:

Windows 8 Consumer Preview ISO images – Download and create your bootable DVD from here:
http://windows.microsoft.com/en-US/windows-8/iso

English
64-bit (x64) Download (3.3 GB)
Sha 1 hash: 1288519C5035BCAC83CBFA23A33038CCF5522749

32-bit (x86) Download (2.5 GB)
Sha 1 hash: E91ED665B01A46F4344C36D9D88C8BF78E9A1B39

Download ( http://www.slavasoft.com/hashcalc/ ) Install and run HashCalc, from the HashCalc "Data" box click on the navigation button to locate and select the consumer preview .ISO file. Place a check mark on in the SHA1 box and click "Calculate". The returned hash value (not case sensitive) should match the value posted by Microsoft. This is your means of assuring the file was not corrupted during the download.

Next you need to use the .ISO file to create a bootable DVD used to install Windows 8. Another good utility for this job if you don’t already have the necessary software (Roxio Creator and Nero being two of the more common ones) is ImgBurn:

http://www.imgburn.com/index.php?act=download

There is a good set of screen shots to help you use ImgBurn: http://www.imgburn.com/index.php?act=screenshots

Note: Always use quality DVD+RW media and the slowest burn speed possible for your model of DVD burner to insure a good burn is achieved.