Gel GVP312GB1600C9TC and OCZ OCZ3G1333LV2G compatible?

Hi, I'm having already an OCZ Gold memory 6GB part: OCZ3G1333LV2G on motherboard MSI X58-m and i7 920. I was wondering if its possible to add to that system a Geil modules 12GB code GVP312GB1600C9TC (received today in newsletter )

I'd would like to avoid some incompatibility issue, ie your help is highly appreciated before I'll decide to order it.

Thanks in advance,

Regards,