I'm tring to istall Ubunto on HP ProLiant ML150 G5, there are after powering on the server 8 beep and nothing apens. How to solve that problem; I don't if make a mistake on RAID configuration.

Make sure all memory modules are properly installed.
and they are install with the guide that came with the server
remenber that most times beeping on post is caused by memory population mistakes. Here is a guideline
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Please ensure socket 1 is populated, otherwise the system will not boot. Install memory in balanced pairs
Memory must be populated in one of the following ways:

1. Slot 1 only; slots 1 and 2 only (pairs must be of the same size).
2. Slots 1, 2, 3, 4, 5 ,and 6 (pairs must be of the same size and in the example below with slots 1 and 2 the same and slots 2 and 3 the same, and slots 5 and 6 the same)
3. Dual rank DIMMs can only be supported in slots 1 and 2.