I have same problem like subhendu
I bought seagate hdd 3 weeks ago, it's works fine, but after several days, his speed in hd tune benchmark dropped from 118mb/s to 3mb/s!!
I check hdd health status and i saw this
Ultra DMA CRC Error Count
Number of interface communication errors:2
I changed my hdd, but after several days, new hdd started same problem
I changed power and sata cables and test in another sata port, but problem did not solved
can you help me?
Sorry for my English.