VMWARE - ULB - PROBLEM

[VaLeyyy]

Hello community. I am currently having some major problems with my virtual machines, first of all I'll create a list to show you what my hardware is, in the next step I'll tell you how many VM's I am actually able to use with this setup and then Ill ask you if you'd suggest me to buy some new hardware.

HARDWARE:
i5-2500K 3.3GHz - CPU
8GB DDR3 1666MHz - RAM
PCS+ HD 7950 3GB - Graphics Card
1TB Hard Drive and 500GB Hard Drive
5600rpm and 7200rpm

At the moment I can only run 4 VM's without having any problems, crashes or anything, as soon as I start a 5th one my VM's start crashing and doing things that seem quite annoying to me.

I was thinking about buying another 8GB of the RAM I already have, would that make any difference? Can I even run 4 VM's or even more on my current hardware? Is it normal that I crash that much?

[kosiarzxx]

u need SSD hard drive,

normal HDD can max ~3 machines per drive

[Lifeban3]

Bots usually tend to get unstable when you use more than 4 on the same hdd.

[VaLeyyy]

How are others able to run 10-15 vm's on one HDD then? I mean even my friend is running 10 on one HDD. The only difference is, that he has 16GB RAM, while I only have 8. How many VM's could I run on a SD? What else could you suggest?