Both of these units have identical specs, so what we need is the specifications that make them two different models from the same manufacturer; please post all specs for each unit. Especially check on how much L2 and L3 cache you are getting on each CPU, that can really make a super difference on performance. The specs you posted indicate a separate video card, not integrated video on the motherboard; make very sure that is the case, in games and CAD programs the video card plays as much a part as the CPU and amount of memory.
run my engineering softwares...and would play those average games.
This is the critical point. I don't know what engineering software you are referring to, but if it is a CAD program of some kind you probably would get it to run, but slowly. Especially if you are going to do a final render on your project, that can take hours and possibly not complete at all depending on what you are doing. Carefully check the hardware requirements that your engineering software posts as basic requirements, and then "bump up" the requirements for a reality check. For example, if it specs "Windows 98 or better" as the operating system, then for it to run properly you will need minimally Windows XP; if it says it needs 1 gig RAM, then it will need 4gigs of RAM for top performance, etc. etc.
As far as "average" games go, remember that gaming drives the personal computer industry. Games apply the greatest stress of any software out there, so I would not expect too much excitement. You may have a lot of dropped frames in intensive scenes. There really are no "average" games; the gaming industry is fiercely competitive and are striving to outdo each other, so everything out there requires serious hardware, especially if you are gaming online.
Edited by ranchhand3, 12 September 2012 - 09:22 AM.