The type of softwares you run, for best performance, go for i7 CPU (can utilise quad core). Catia, Solidworks, for best performance, need GPU with certified driver (those Quadro, Firepro thingy), but can also utilise normal consumer GPU for 3D (but I understand you may lose some functionality).
I suggest you go for 15", with i7, discrete GPU, FHD (for workspace).
Sacrifice light weight for better performance. Powerful machine inadvertibly will get warm in laptop form factor, get good external cooling solution

Dell
Inspiron 15R, i7-3517U + AMD HD8730M + (1920x1980; anti-glare)@RM3199[2.32kg], 8GB, 1TB(5400rpm), W8SL (CPU is only duo core, GPU also weaker, but is lighter than the 15R SE)
Inspiron 15R (Special Edition), i7-3612QM + AMD HD7730M + (1920x1080; anti-glare) + 32GB SSD + 1TB HDD(5400rpm)@RM3199, 8GB,backlit keyboard optional, W7HP/W8
Lenovo
Ideapad Y580, i7-3610QM + Nvidia GTX660M (2GB) + (1920x1080) + Bluray@RM3499[JBL], 8GB, 1TB HDD(7200rpm), W7HP, backlit keyboard, 2 years international warranty
Extend / upgrade warranty to 3 years on site (best warranty support you can get for laptop in Malaysia)
Price is RSP, negotiable.
thank nexus but is there any laptop from hp, asus and toshiba that suitable..
i want to look for all the manufacturer..
And what is your suggestion for external cooling..
And how about if 14"..