I was thinking about building a PC with the same specs of the
most powerful Mac Pro (about $18,000 )
The specs follow this:

> 16 GB Ram
> Intel Quad-Core 3.0 GHz x2= 8 cores
> AirPort
> SuperDrives
> 3TB Hard Drive

Of course, using a server mobo.
Do you know if it is possible,
do you know about hardware and software limitations for OSx86

Thanks in advance for any information.

What will you use it for ?

If you are building this to be primarily a PC with occasional Mac useage, I'd say go for it. But if it is to be primarily a Mac, it's not going to save you that much over just buying the base dual 3.0, 8 core from Apple and adding your own drives and ram. I mean what happens when Leopard finally comes out and it doesn't work on the multi-thousand dollar Hack? It's guaranteed to work on the real thing. I own a Mac Pro and a pretty powerful and stable Hack. Right now, they run neck in neck with each other. Not sure what's going to happen when Leopard arrives...hopefully in October.

You will not save too much if you assemble this system by yourself. Only spent some extra time (and money) to make system silent and cold.
Better to go with natural Mac Pro. And follow advise of BJMoose. But if you'll add non-aple memory, don't try to save on it.

So it's better to buy it directly. Thanks.
Also, how much ram does Mac OS X support?
For example, in Mac Pro you can add up to 16 GB,
it is normal Mac OS X, or do you have to use Mac OS X Server?

Surfing porn... OS X (the base system) is the same for OS X and OS X Server ... sure server has other APPS that OS X doesn't but at the lowest level it's the same code. So if OS X Server can utilize 16GB so can OS X...

And oh yea.. I have to agree with the gang... when you're looking to 'exactly' duplicating a Mac Pro ... you're better off IMO to just go with the Mac model... The 'Apple premium' isn't all that great over building it yourself...Where this project comes in SUPER HANDY is for folks like me who REALLY want Apple to release a 'headless imac' aka 'mac mini-tower' model where you have SOME expandability when it comes to CPU choice and video card options... With Apple you are either stuck with a super low end mini with substandard video (for gamers) and a monitor of your choice... or a 'somewhat palatable' video card for gamers but forced into a display of Apples choosing... *or* paying for a super high end system....In short, they leave the 'middle of the road' totally out of their line-up... Providing a demand/need for the OSX86 Project!

The thing to remember is SHOP AROUND (newegg/frys/etc) for additional RAM and HDDs (over the 'base' config) since Apple will charge you an arm and a leg as compared to what you can get the stuff for elsewhere. You just gotta invest the time in researching with other Mac Pro owners as to what 3rd party RAM HD works best and/or should be avoided.

Dave