Some of our company PC’s link speed limited at 10Mbps and 100 Mbps

Hello all , We are using HP and some Cisco switches for our company, we faced this problem , all switch ports are 1 Gbps speed and auto negotiation, all pc also auto negotiation but some times we faced this problem link sleep limited at 100 or 10 Mbps , what i already tried : 1-forcibly made all pc to run at 1Gbps (not worked) ,and some of them don’t even have 1Gbps option in their link speed ,i added by windows register but still not worked 2-try different cable (not worked) 3-try same port for another PC that had 1Gbps speed but still not worked

my question what should be the reason for that problem ??????!!!!!!