So, at work, we've got a pair of HP ProLiant servers, and like many modern machines, most of their slots are PCI-E and they've each got one legacy regular-PCI slot. Says so right on the sticker inside the case cover.

But when we look at these motherboards, it looks like each of their regular PCI slots are mounted backwards, whereas the PCI Express slots seem correct.

Here is a photo from the Wikipedia article about PCI Express, compared to a photo of one of our ProLiant boxes. Note the position of the divot, indicated by the red arrow in each photo.

Are these boxes truly backwards, or is this some oddity of the PCI standard we don't know about? Our PCI cards don't fit in this slot. (Well. They would fit if we took the bracket off the card. But we're afraid to try for fear of shorting things out if the slot is truly soldered into place backwards.)

(Wikipedia Photo First):

If you were on Wikipedia you were one click from the answer: http://en.wikipedia.org/wiki/Conventional_PCI#Card_keying

The upper photo is 32-bit 5V PCI, the lower one is 32-bit 3.3V PCI. Most cards are dual-voltage and have two notches in order to fit in either.

Peter

Dayamn.

Peter

Terse wins.

Too awesome. Thanks guys.

Your little race-to-post was a subject of much amusement to my coworkers here.

"They're my peeps", I tell them.

I'm glad I checked the thread before digging up the same wikipedia article. Though I probably would have been distracted by trying to identify the Proliant model. Is it an ML300 series?

Close. ML-150 G6.

I woulda been faster, but for having been distracted by the "awesome" yellow connectors.

Ahh. Never supported the 100 series servers, due to them being rebadged HP servers after the merger. By the time they were fully integrated, I had moved onto storage.

You were a Compaq guy? Blurgh.

I take no responsibility for anything Compaq did outside of the Proliant realm. Though amusingly, the site I worked at was an old DEC site, and most of my new hire paperwork still said Digital, 18 months after that merger.