I have a client that has an ecommerce website on xcart and a blog on a subdomain but on a different wordpress site and server (separate ip addresses) .
What is the impact on Google SEO Ranking and should I encourage the client to move the blog to the same ip address?

Fictitious Example:

www.clientxcart.com (ecommerce site) ip 149.320.23.4

www.blog.clientxcart.com (blog) ip 132.32.23.2