Vostro 3500 RAM Upgrade limitation

In the manual of Dell Vostro 3500, right here, I found that only systems configured with a discrete graphics card will support RAM card with 3200Mhz.

Does that mean if I install an additional RAM card which has the speed of 3200Mhz,

* it won't be usable within the system ( that it won't be responsive or completely incompatible with the system ) 
                                                 OR
* it won't support its mentioned speed ( which is 3200Mhz ) but will be compatible and usable as a RAM card which   has the speed of 2666Mhz?

Thanks :)