Hi, there. Sorry for reading your words so late.
P5E3-P is a friendly mobo for Celeron D by no mod.
You may get your Celeron D work on RE X48, firstly you need FSB 533 to 800 mod, secondly you should make sure your CPU can post at such high clock (50% overclock) .If not, you still need Vcore mod, done by VID mod or mobo mod