do you have an extra powersupply to try?

tried different power supply, same problem

have you done any upgrades to the server

no, recent upgrades have been done,

I would try reseating everything to start to see if it is a bad  or dirty connection.

power is getting to the MB because it has lights plus the front panel has lights, i am guessing it is a fault with the MB, just wondered if anyone knows what the flashing lights mean ?

http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?lang=en&cc=ca&taskId=110&prodSeriesId=502439&prodTypeId=15351&prodSeriesId=502439&objectID=c01110778

http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?lang=en&cc=us&objectID=c00429380&prodTypeId=15351&prodSeriesId=502439

its the internal lights that are flashing, i cant find any docs that explain them

The following is every led for the G3 I beleive that they were close to the same. On the Hp site it goes through each led by where it is on the board and tells you how to troubleshoot for each light.
http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?lang=en&cc=us&objectID=c00363246&prodTypeId=15351&prodSeriesId=502439

My last post link has the internal led on a g3 server. I can't seem to find for the g4

http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?lang=en&cc=us&objectID=c00328957&prodTypeId=15351&prodSeriesId=502439#{#DOC%20c00319960#}#

sorry last post for wrong server

Manual is here, http://bizsupport.austin.hp.com/bc/docs/support/SupportManual/c00576048/c00576048.pdf LEDs are on page 59

... i do have power lights on the front panel....
If it is green this indicates your power supply is OK. If the power button show amber color, could be fail power supply, memory, or motherboard

....when booting the LED's on MB CR2,4,7 and 10 come on, CR 13, 14 flash alternatley
Unless they are red or ember color to tell you the part is failed, all flashing green LEDs are OK (just indicated you have activity going on)

Suggestion:
You may want to bring the server down, unplug and hit the power button to drain all the power. You then take out some memory dimm and reseat the remaining dimm. Try to boot it up with small number of memory and swapping your memory to detect a bad dimm. If you have spare dimm, replace with spare only.

K

the server is currently down, powered down completley, removed DIMM, drained power same problem.
I dont even get the initial beep or fans whirling into action when it boots up

Does anyone have any idea, i get no Red or Amber lights on the system board which would indicate no failures, just flashing green which would indicate activity.
I have drained power removed all memory removed bios batt, still getting no POST. ?

I have drained power removed all memory....

HP server will not boot if there is no memory installed. I have seen a server with your situation and it boots fine after installed new dimm. Do you have a spare dimm? Call HP if you still have warranty on it. They will replace failed component for you even your MB.

K

If no dimm is installed i was under the impression that a series of beeps are given ? however i dont get this, which leads me to think it's not the DIMM