Suche Nachfolger als SysAdmin in Berlin

Dear lazyweb,
for my soon-to-be ex-job I need a single core CPU for some mathematical optimization software that is licensed per core. We have a single core license and therefore a single core or a dual core would be sufficient. The CPU should have as much power as possible with as mach L2 cache as possible and it should be 64bit. 19″ rack equipment (1 RU) would be nice.

Any suggestions for the hardware?