Can CPU Access Hard Disk ?

No, the CPU cannot  access the hard disc. A storage controller (RAM, for example), which controls data transfers between the hard drive and the CPU, is used to link the hard disc to the motherboard. The storage controller is frequently built into the motherboard chipset, although it is also possible for it to be a separate card that is inserted into a motherboard slot. Hard discs use magnetic platters to mechanically store data. Without any additional hardware, a CPU can directly access a hard disk. Data transfer speed and physical size are the hard disk's two main problems, though. The hard disk's transmission rate drops as its capacity does. The hard disk's physical dimensions also restrict its application in compact devices like smartphones and tablets. Therefore, when using a hard drive, it is crucial to have a strong data transmission speed and low power consumption. Even while it is feasible to directly access a hard disc, doing so serves no purpose.