Sempron 145 or AMD A4-3400 for Minecraft Server

I have recently started hosting a minecraft server on my main computer. It was all going fine till about a week ago, when, I started to grow a community. I need a separate computer to host the server and am curious about these two low-end processors (Will be pairing with 4gigs of 1600mhz 1.5v ram that I have laying around.) The minecraft server only uses one core, and the A4 is clocked lower, so, would the sempron be better? Input and criticism would be appreciated!

a4 but the sempron would work too my first server was run off a singlecore sempron with 5 people on the server no problem.  The a4 will be better because of it being a dual core.  I now use a triple core phenom and It will use more then one core if you give it more it will spread the load across the cpu cores.

Minecraft will destroy that cpu... a phenom ii x 4 is relatively cheap or even a amd athlon ii x 4

Hes talking about a server and I have use a sempron to host one and now use a phenom x3 and the only server that can max my x3 is a feed the beast server with 5 people with chuck loaders in the nether and quarries running.  The single core will be fine but try and get the a4 5400k and overclock it. 

I'll look into that, thanks!

I understand that its a server,a mate of mine runs a server but not a home server he rents a dedicated server from OVH/Kimsufi (100Mbps/100Mbps,i3 2130 3.4 + GHz,8 GB ram,2x500gbs raid) and he has started maxing out the server and thinking of upgradeing alltho i am gessing its all down to how meny players you have and how big your minecraft world gets(ive never realy been in to minecraft)