cpu upgrade = no boot?

ok, so i have this old PC i got in like 2000..and i've been steadily upgrading it. more ram, new geforce 6800..
so i bought a new CPU.
my old one is a p4 1.5ghz, 400fsb, 256 cache.
this one i bought is a p4 2.6ghz, 400fsb, 512 cache.

full specs:
it's rockin an ASUS P4U-LA. 768 sdram pc133. 2 optical drives,if that matters. antec truepower 430. nvidia geforce 6800. audigy platinum ex. 2 hds. and a partridge in a pear tree.

i put the chip in and i get NO post beeps. fan spins, HD spins...that's all.
i put my old chip in and it boots just fine.
i tried stripping the power out of all the other things, hds, vid card, to see if my 430 watts wasn't enough (?), but it still didn't do anything.
i took the ram out one by one, no change. then i took it all out and got a bad ram post beep
so i think newegg shipped me a junked CPU.
i know *I* didn't burn it, cuz i'd have smelled burned chip/thermal grease.
any other ideas?
i basically want to know if it could be that my mobo doesn't like the chip. cuz if that's it, i'll just get my cash back. but if it should work, i'll get another chip.

Maybe your motherboard doesn't support the 512kB cache... Well unless you're realy on a budget I suggest you upgrade your system to 800MHz fsb... You can keep your old chip for now and return the new one to buy a motherboard which supporst that fsb speed. Then, when you have the money get a 800MHz fsb processor!!!

I don't think that mobo can handle that new CPU. I don't know about the P4U-LA, but the P4U's I used to work on in HP's... like Pavillions and Vectra's. Those were OEM made by ASUS and ASUS wouldn't support them directly. I think the highest they went was 2 Ghz, or maybe a little more with a bios update. The voltage is probably all wrong between your mobo and chip. I'd try a 2 Ghz 256 cache unless you can find a bios update that'll give you more.

Besides, HP had a pretty bare bones mobo since these went into machines basically built for corporations (spreadsheets and whatnot). I think getting it to 2 Ghz with the upgrades you already listed will be about as good as that dog will hunt.