> and i'd like to know if i can finally play those nasty 3d games such as cyber cycles
> and the likes at a decent speed,like many videos on youtube shows
Cyber Cycles is a Namco System 22 game, so that setup should be able to do quite well with it. I'd be surprised if you don't get full speed.
However, those "Nasty 3D games" cover a wide variety of hardware configurations, and it's impossible to give you a specific answer without knowing exactly what games other than Cyber Cycles you plan to run.
Playstation-based games (like Tekken and Star Sweep) should work great, as well as Atari/Midway Seattle games (like NFL Blitz). However, platforms like Naomi and Aleck 64, which are based on the Dreamcast and Nintendo 64 respectively, won't be able to run full speed with current MAME on any modern hardware, regardless of CPU.
If I can offer one suggestion, I would bump the amount of RAM up to 16GB if you can afford it, assuming you would be playing PC games apart from just using MAME. 8GB will do just fine for MAME, but with PC games, having the extra RAM can be very useful.