I would recommend contacting Lenovo since there are no specifications for your Intel(R) chipset here: http://shop.lenovo.com/us/en/desktops/essential/h-series/h520s/# tab-tech_specs Lenovo H520s - Affordable Small Form Factor Family PC | Lenovo US
If you get the chipset model you could access http://ark.intel.com/ ARK | Your Source for Intel® Product Specificationsand see Compatible products, there you will see a list of possible compatible processors. Please bear in mind, this type of compatibility depends on the computer manufacturer.
Allan.
