So if i was to run a MySQL / PHP driven website and i'm receiving thousands of hits per day. Which out of the two will help the site to load faster? If i was looking to purchase a dedicated-server to host the site on which would matter more in achieving what i'm after? The CPU or RAM?
You're not going to get a definitive answer. It's like asking, "I want to drive fast, what's the most important, petrol or the tyres?" Both play their parts. RAM is cheaper than it's ever been, and CPU's performance has increased hugely over the years. Not having enough RAM or CPU is bad. Get enough RAM so that it isn't all used up when the system runs, then get a powerful enough CPU so that it isn't maxed out. However, you've missed out the most important part - "a big enough engine" - and when it comes to databases that is the DISK performance. No matter how much RAM, or how many (or powerful) CPU's you put in, they are always going to be limited by the performance of the disks. Forget size (you don't need huge disks) think performance - SAS, 15K, Hardware RAID, and RAID 10 min will do the most for your system...assuming you have enough RAM and CPU performance. It's not just about one thing, but how they all work together.