Hello, yes 32gb will work on your R2 (2x16gb).

I believe Dell only officially supported 16gb as being the max configuration but people have got 2x16gb to work well.

You can also check out the Crucial website for options

https://www.crucial.com/compatible-upgrade-for/alienware/alienware-15-r2#memory

Hi @panos34g   welcome to this user to user discussion forum.  This is not Dell Support.

Dell Support for Alienware 15 R2 Specifications was published in 2015 and Dell do not keep updating their documentation. Asking Corsair to recommend your RAM upgrade is good, because if it does not work out they will accept returns and give refund. You may want to ask Corsair to recommend the maximum RAM upgrade, to assist with your purchase decision. Guess you could purchase 2 x 32 GB = 64 GB with a higher speed. If this does not work out, return the 32 GB card. Corsair is usually willing to discuss your options.

Windows 10 gives users the option of assigning virtual RAM. An ultrafast NVMe Gen3x4 drive will give a good virtual RAM speed, but never match the fast speed of the actual RAM cards. Still worth considering your virtual RAM options. 

Please click on Kudos to say thank you for response from another user. Please share an update on progress, so that other users derive benefit from your experience. Thank you.  

It will work with corsair value select 32gb DDR4 2133MHz this is 2x16 can i buy it and upgrade my system ?

My ram arrived today it is working perfect and ive noticed that the performance of the system is much more better than ever before. The original ram from the factory had poor performance . It worth the upgrade corsair and gskill has always the best rams on the market . Thanks a lot guys for your help i appreciate it !

Hi @panos34g  thank you sharing the good news. Please tell the Dell Community what RAM was purchased, so that it can help other users. Thank you.