Power steering fluid - bone dry
 

1999 purchased new, I've never checked the level but thought I'd do the old suck out and replace a few times when I had access to the engine to change the air filter. Well, nothing on the little dipstick, not even a drop or a sign of any fluid. Car is perfectly level and I have no issues with steering. I'll put some in up to the cold mark and see how much it takes to get there. Anyone see this before, I guess after 18 years it's bound to go somewhere.

mine was empty first time I checked it also, topped it and it improved (but didn't completely fix) the groans on hard reverse turns, been ok since. My guess is as it's a pain to get to most previous owners never check it, so over the decades even a slight leak results in an empty reservoir.

The o-rings on the reservoir can eventually dry out. You can replace the reservoir which comes with the new rings, or just buy the new rings. The first option is not too expensive.

There are two reservoirs. Upper and lower. The lower is a pain in the a$$, but doable. Lot's of sentence enchanting words, removal of the crossover intakes, TB, and partial removal of the A/C compressor is involved. Usually, the main reason the upper is dry is the PS fluid has puked out (too hot and expanding) of the overflow tube, right on top of the engine. Makes a complete mess, and is also pretty difficult to clean up as there are fairly deep nooks and crannies on the top of the engine. I love my Boxster, but Porsche didn't do a great job with the PS design. If you track your car, the issue can be worse.

I ended up installing a metal canister to contain the ejected fluid after chasing imaginary PS leaks:) and trying to clean the fluid on the top of the engine:( I used a metal fuel filter (blocked on one end) and a hose connected to the overflow nipple on the top PS reservoir. I do have a UD pulley as well.

I thought of something like that, but couldn't come up with a good place to put the canister. Where did you put yours? Pics by chance? I went with the UD pulley as well.

This has been covered before.
The O ring selection is tricky to get the right size. It is easy to accidentally loosen the bayonet twist fitting on the reservoir.if you are working on other components in that area. The selected 'O' ring(s) need to be a tight fit in the groove but as plump as possible to prevent lossening. Lube the O ring with liquid soap to get it in- not grease/oil. The objective is to make the o ring slick for a few minutes and then sticky in service.
The stock overflow hose is too short. Use a longer one with small catch can to ensure you know if the mess is overflow(if any) or O ring leakage.