I've just read this article, which claims that MI5 found backdoors in Lenovo built PCs:
Machines produced by the state-backed technology company, which is the largest PC producer in the world, are claimed to have been found in tests by MI5 and GCHQ to have modifications in their circuitry which could allow remote access to the devices without the owners’ knowledge.
Scientists are claimed to have identified highly-classified “back doors” in chips used in Lenovo machines which are extremely difficult to identify and could be activated remotely to either stop targeted computers working or access their contents.
Is this true?