Cheapest best motherboard for intel e7500

Depends on your vender, memory, and case size. I have an old g31 that still works fine; the newer version is the g43. For an atx case, check for p45 closeouts or rebates at newegg. These are good for ddr2. For ddr3, the x48 boards will work. Need support for both, then checkout the asrock boards, which allow you to use either ddr2 or ddr3 on some models.

watch memory voltage

It's ok for basic usage. G43 gives you some hdmi support if you like to watch videos.