The default frequency for Phenom II CPUs including the 1090T is 1600 Mhz. There is no way to make any RAM run faster than the default CPU RAM speed without overclocking it. The RAM speed rating just means the RAM has been tested and confirmed to run stable at that speed, voltage and timings listed on the label -- when run in a test fixture.
To TRY and OC the RAM to a higher speed than 1600 Mhz. you need to go into the BIOS and change the RAM frequency, latency timings and voltage settings to match the label on your RAM. Remember OC'ing is NOT guaranteed to work and you can end up with BOSD, lost data, corrupted files and a lot of sorrow.
It's also worth noting that OC'ing DDR3 RAM produces a VERY very small performance gain of ~1% in my testing and is hardly worth the effort if there is ANY stability issues after the OC.
http://www.hardwaresecrets.com/article/152