Upgrade Graphic card for a Hp p6240f

The official short for for micro-ATX is mATX. Sometimes the greek letter µ (Mu) is substituted for the word micro, particularly for scientific purposes.
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

^ That PSU will work for you.

It really should work. Try restarting your computer, when it restarts hit F10 for set up. Use the arrow keys to take you to the "advanced" menu. Highlight "Primary video adapter" using the arrow keys and hit enter, use arrow keys to take you to "PCI-Ex16" enable it. Exit and save changes(should be F10 again). After it starts shut the PC down and install the card and reboot. I hope this helps i've used that same card (4670) in 2 HP PCs and haven't had any trouble.

He said he wasn't getting any startup when he hit the power button. If his PSU is from a prebuild computer (which it obviously is) then it won't work; they're simply horrible.

It's a new PC wanted to upgrade the card with out upgrading the Power supply.. When i installed the card i heard and saw the Graphic card fan move but no go it would not turn on...Hp and The nice ppl from this form said it would work... So Now i have to find a better power supply i guess?

It's a Bestec 300w PSU, standard ATX. It should have no problems. Make sure the card is properly plugged into the PCI-Ex16 socket and clipped in place. There's a chance that a SATA plug or 2 may be interfering with it. If so turn off the PC, switch to another plug that won't be blocked and reboot. Make sure your Monitor is plugged into the new card, not the old integrated plug.

Well installed the card again..did the f10 thing changed the adapter in setup.restarted and nothing happen...Iknow now I need a bigger Power supply...that sucks