I'm not sure what you mean by mobo, so I will give you more info. My system is a emachine T2682. I have 512 mb ddr ram installed at 333mhz speed for a 2.6 ghz celeron processer. I bought 1 g of ultra brand ddr memory that is is 400mhz speed that has the same pin configuration to fit in my computer. My question is will it downspeed to 333 mhz? I just installed a radeon x1300 video card, and am trying to update this out of date computer enough to play battlefield 2 on the lowest settings. I don't have experience in updating, so all this is new to me, and I don't have the $ to get a good gaming computer, so here I am.