Small Form Factor (sff) Pc's are not conducive for GPU mining, simply because o don't accommodate any standard/large size GPU cards. Depending on the size of the lenovo sff pc you've got, they won't fit any vid cards except the low rise vid cards which won't be the cards you want to run for monero or other crypto mining. Your best bet is a ATX size, at lease medium size, PC cases, not SFF.