freeware for extracting RAR files for windows 8

You've answered your own question. Use WinRAR.

You could also use 7zip. It opens zip, rar and 7z files.

Going by the @OP's posts in the past and this one, I don't think he ever uses google.

Use 7zip

I personally prefer 7zip because its open source. Also, it has support for multiple compression algorithms.

^ but to unrar the .rar files which were created using Winrar 5, he'll require winrar 5. Nothing else works on them, not even 7zip.

DeSmOnD dAvId said:

I personally prefer 7zip because its open source. Also, it has support for multiple compression algorithms.

Click to expand...

+1, for this exact fact and comment.

SaiyanGoku said:

^ but to unrar the .rar files which were created using Winrar 5, he'll require winrar 5. Nothing else works on them, not even 7zip.

Click to expand...

+1, for this true comment also.

Fact is, I use both 7zip and WinRaR, as accordingly.

SaiyanGoku said:

^ but to unrar the .rar files which were created using Winrar 5, he'll require winrar 5. Nothing else works on them, not even 7zip.

Click to expand...

That's probably because no one has reverse engineered the new RAR algorithm yet.

WinRAR is not a freeware, even though it behaves like one.

yep it is trialware / nagware

use peazip.

I think winrar is optimized to use multiple cpu cores? 7 zip?

depends on the compression algorithm used. ANyway, this link should be helpful :
File Compression in the Multi-Core Era