Strange. I can't find that part number or "Rendition" model name anywhere on Crucial's site. Maybe it's old/discontinued stuff?

Looking at their site, most of the current PC2-5300 is 1.8v, CL5. I'm highly suspicious of what you bought, to be honest. There is a lot of 533MHz stuff at CL4 that is "overclocked" to 667MHz from what I can see, which is disturbing. I'd be on the phone with Crucial finding out WTF you bought. :P