only the first part of the archive (e.g., 990OPSR1x64.part1.rar or 990OPSR1x64.001 ).

Are you trying to install this on ?

Multi-part RAR files are split into smaller segments to make downloading easier. You download every single part (e.g., 990OPSR1x64.part1.rar , 990OPSR1x64.part2.rar ... or .001 , .002 , etc.) and ensure they are all located in the same folder. 2. Install Extraction Software

Here is how to download and reconstruct (make a piece) these types of files:

What is the specific of the download (e.g., .part1.rar , .001 )?

If you get a "CRC failed" error, it means one of the parts did not download completely. Re-download the specific part causing the error.