I have an emachines w5243. The motherboard failed and I swapped it with an ECS c51g-m754 board. I installed mobo drivers and no sound. I installed realtek alc655 drivers and still no sound. I have sound through the headphone jack (on front panel) but no sound through the onboard I/O port. Running Windows Vista Home Premium. Any thoughts?

Does it have realtek ? If so and it has other outputs like digital then the default may be set wrong to how you want to use it. Check to make sure that "port" is active. Realtek has a program for that.

Well off had, you said you had an emachine w5243. That probably had a mcp61sm-gm motherboard, Which is a socket AM2. Your ECS c51g-m754 board is a Socket 754. The emachine came with Vista but the socket 754 board is windows 98/XP compatible. Not sure you can get Vista drivers for it. Put windows XP on it and you should be fine. Personally if just your motherboard went I would get another socket AM2 board and put the processor and memory from the emachine board, Then you'll be vista ready again.

Well off had, you said you had an emachine w5243. That probably had a mcp61sm-gm motherboard, Which is a socket AM2. Your ECS c51g-m754 board is a Socket 754. The emachine came with Vista but the socket 754 board is windows 98/XP compatible. Not sure you can get Vista drivers for it. Put windows XP on it and you should be fine. Personally if just your motherboard went I would get another socket AM2 board and put the processor and memory from the emachine board, Then you'll be vista ready again.

While you are correct as far as the MOBO initial specs go for the m754 MOBO (it was primarily designed to be run with 98/XP). Beings you can install Vista on these they do have drivers for the Realtek ALC655 codec which is the driver this MOBO needs. The issue is not being able to find a driver (because they do exist).