RAM not running full-speed

[Apk07]

I have a Dell E510 with a 0RD203 Motherboard, latest BIOS.
Yes, I know this PC is old, but I bought this RAM for it quite a while ago. 2x 1GB DDR2 533 (PC2 4200).

For some reason, CPUZ (or PC Wizard 2010 now, I guess), reports the RAM is only running at 266MHz, when this RAM is supposed to be 533MHZ. This is what it says exactly for 1 of the DIMM's:

Type : DDR2-SDRAM PC2-4300 (266MHz) - [DDR2-533]
Format : Regular UDIMM (133.35 x 3)
Size : 1024MB (2 ranks, 4 banks)

Now this same program also says my mobo/chipset (Intel i945G/GZ) supports up to 667MHz RAM:

RAM max. Support : DDR2 (667MHz)

I've seen random sites across the web say it supports either 400MHz or 533MHz. Which is true? I have no idea what to trust here. This RAM has been running in my PC for a couple years now, but I'm just now finding out it might be running at half speed?

 

[o1die]

Cpuz reports the ram speed as half what it actually is; many motherboard bios also do this. So multiply your reading by two and your ram speed is correct.