Need some data to proof if putting the SSAS server and the relational db on the same server would be a good idea or bad one

We are now having everything on one server, but we plan to have them separate.  In order to do so, I need some hard proof - something maybe like a white paper or something - to support my assertion for applying for the new hardware.

The initial reason why we want separation is because we have observed some high resource contention.

We definitely will have failover or NLB if we decide to separate the SSAS server.

Mainly from the disk, but in general they are all at a very high level.

Thanks.