RAM doesn't show as 1333Mhz in MP 4.1

[Flocarino]

I got 24GB of identical OWC 1333Mhz RAM and it only shows as 1066Mhz in my Dual 2.26Ghz MacPro Early 2009 4.1, updated to 5.1.
Zapped the PRAM to no avail...Did I missed something?

 

[beto2k7]

Xeons E5520 (the ones you have) only support 1066mhz ram

 

[Flocarino]

Xeons E5520 (the ones you have) only support 1066mhz ram

Allright, thanks.