Monitor goes to sleep whenever i change or add ram

In the name of that memory module is 1RX8. In the manual for that computer:
http://h20565.www2.hp.com/hpsc/doc/public/display?sp4ts.oid=4047714&docLocale=en_US&docId=emr_na-c01942289

page 6:

"DIMMs constructed with x8 and x16 DDR devices; DIMMs constructed with x4 SDRAM are not
supported"

Also, google searches seem to indicate that the other posts are correct about you buying ECC memory, which is definitely not supported.

Sorry, but it would seem that you bought the wrong memory module. You need to make absolutely sure that you have identical modules in both memory slots on the motherboard. Also note that memory modules that did not come together in a kit are never guaranteed to work together even if both are similar and individually supported by the motherboard. You should buy a 2x2GB kit meant for your computer if you want 4GB of RAM.

Does the preinstalled memory module have a sticker on it and if so, what does the sticker say?

Also note that you must shutdown the computer, unplug it completely, and wait at least 30 seconds before changing internal components. This is also stated in the manual. Changing internal components while the computer is plugged in, let alone turned on, can cause permanent damage to the computer.
 
AHHHHHHHHHHHHHHHHHHHHHHHHHHHH IM SO DUUUUUUUUUUUUUUUUUUUUUUMB AAAAAAAAAAAAAAAAAAAHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH LOL
 


lol its certainly not the dumbest thing i have seen by a long shot

so just chalk it up to you learned something new with no damage done

 
It's a very easy to accidentally order ECC RAM since many computer users don't even know what ECC RAM is since its usually used for server class equipment (Xeons, etc). I've also noticed some online shopping sites don't even mention it; meaning you have to look it up by model number.