Why we don't use RAM drive as the Hard Drive Disk?

I'm very interested in computer mechanic and I'm wondering why we don't use RAM as Hard Drive Disk ? I mean, a RAM of 200 Giga for example as Hard Drive Disk to faster the computer experience ?

4 Answers

Because RAM is a volatile storage device, most kinds of RAM on computers lost all data when it lost power.

There do exist some software that can create a RAM disk for you to storage data. However, it is not recommended to store any valuable information on it just in case a power loss.

RAM is fast but expensive, storage is slow and really cheap.

Given that 32GB of RAM currently costs about £300, 200GB would cost in the ballpark of £2000 instead of the current price of £65 for 2TB of spinning rust storage or a similar £50 price for 256GB of SSD.

This is on top of the volatile nature of memory that Zhongjie mentioned. Besides which if you ever lost power you would need to reload that 200GB of memory from somewhere, and that's going to be either an HD or an SSD or another slow storage device.

Aside from what Zhongjie Shen said in their answer, there are other important points to consider:

• RAM is expensive compared to slower storage. For the 100 USD that a 4TB hard drive costs, you can only get about 8-16 GB of RAM, which translates to it being almost 500 times as expensive per unit storage. Extrapolating this, a 4TB block of RAM with equivalent performance to what you have in your PC would be on the order of 50 000 USD. Nobody outside of government or research work can realistically afford that expensive of a computer. In comparison, SSD's are about eight times as expensive as hard drives per unit storage right now.
• RAM is power hungry to an almost comical degree. That same 4TB hard drive I mentioned above uses about 12-15W of power. With current RAM technology, you're looking at a few hundred milliwatts per GB of memory, which translates to a little over 400W of power consumption if you wanted 4TB of storage. This gets even worse when you factor in the cooling requirements when dealing with that much power usage, which would likely add another 50W or so to the total.

Have you researched solid state drives (SSD)? They work on the same principle as RAM (electronic, rather than mechanical), but it's not the same type of memory (think thumb drives). These drives have much faster data access than mechanical hard drives.

Someone without advanced experience in computers could easily mistake an SSD as RAM, since neither are mechanical storage. When I first read the question, I automatically thought the OP was asking about SSDs.

I was going to post this as a comment, but then decided it should be an answer, since it's not really a clarification question.