Anyone with DEC knowledge? Alphaserver 800

[Cpuswe]

Got this cpu-board from a Alphaserver 800. Specs for the Alphaserver 800 says 333,400 and 500 Mhz. But when i remove the heatsink its a 533 Mhz processor there. Why? Is it just downclocked from 533 to 500 Mhz to save manufacturing costs? Was this a more widely used stategy from DEC?

Edit: And the double delta symbols on the chips to the left? I know that one delta is mil spec, but two? NASA spec?

/Thomas