Trying to understand 2D/3D clock differences

[CreepieDeCrapper]

Using Everest to display my video GPU and video Memory clocks (on the OSD), I see that in 2D/desktop mode they are 500mhz/594mhz (GPU/Memory). This is normal and expected for my cards (x1900 Crossfire edition and x1900xt).

When I go into 3D/gaming mode, I'm alt-tabbing back to my desktop so I can see the Everest OSD, and I see that my clocks have increased to 621mhz/721mhz respectively. Again, this is normal and expected.

What I don't understand though, is why is my memory clock rate only being increased to 721mhz when my cards are rated at 1450mhz EACH? The GPU is rated at 650mhz, so I figure 621mhz is pretty much close enough. But the memory clock is running at half the rate, let alone the fact that I have 2 cards, so shouldn't I be getting 3ghz of memory speed?

I'm probably thinking about it the wrong way, so any clarification is appreciated.

 

[CreepieDeCrapper]

Should I post this in another forum? Please advise, thank you!

 

[JPB]

NO, you should not be getting 3ghz speed for memory. Its ddr...just double it....721+2=1442............Looks like the right specs to me

 

[CreepieDeCrapper]

Aha, there's the implementation of the acronym 'Double Data Rate'. I get it now. Also, am I to assume that BOTH cards are running at those speeds? There doesn't seem to be a way to have Everest differentiate between each card.

Thanks x80064.