Having a load of 5 can be a problem. On some servers I have seen the load going above 5 causing email, web, dns etc to work intermittently. I have also seen a load of 5 with out issues. It does depend on the hardware in the server and what you have installed and configured on it... Multiple cores servers function differently under high loads than single cpu servers..
Thanks for that great article! My host was telling me that the server I am on was ok as long as the load was under 10! (Single core CPU) Thinking outloud -- maybe that was why my MySQL and PHP scripts were so taking so long?
It would depend on the number of cores on the server. General rule: server load should be 50% less than the number of cores. So a load of 4 is ok on an 8 core server, though for some people this is high (this includes me).
A load of 800 on an 8 core server can be okay.. Really depends on what you're doing if it's going to be an issue. If you're doing realtime shiz say financial transactions (share trading) a long process queue is very bad because you'll miss a price or something.
General rule of thumb tends to be load < cores otherwise you got problems.. Which of course isn't actually technically true.
This is why we have schedulers at the end of the day...
If you have a high load caused by contention and it's causing issues then you probably should do something about that but just because it's high doesn't mean you have a problem.