The difference between 2 or 4 cores depends on, what they are used for ...
3D-Mark is good for testing overall gaming performance - that's the main reason, why this benchmarking tool got programmed - but not for applications like 3D programs !
If you look through all the tests being done, they are mainly focused on calculating moving realtime 3D gaming graphics - cpu + gpu or only cpu, but that's misleading in the end and only reliable for gamers.
All 4 core cpu's are good for playing games, but there are the fastest 2 cores, which are doing better in gaming, simply because most nowadays games don't support 4 cores directly, because this is a more complex programming in games, due to all of the different things that have to be calculated in games - like graphics, physics, artificial intelligence, sound, playing music, gameplay logistics and so on ...
So that's way with 4 cores, each core only get's used roughly like between 25 to 50 percent of it's power, the rest get's wasted. Still - the 4 core cpu in such a situation doesn't get pushed to it's limit compared to a 2 core, which might be using both cores up to 100 percent. So - a 4 core cpu won't be heating up like a 2 core - meaning overall lower temparature and quieter machine - less strain on the hardware.
If you need a cpu, which is excellent to work with applications like 3D programs, here we need render power - like Terragen, 3DS-Max, Cinema 4D, Vue, Poser ... and all those well known programs more - it's a total different picture !
Here, like the newest build 1.988.1 of TG2, they will use 2 cores or 4 cores to their full 100 percent - but if you have 4 cores run at 100 percent and only 2 cores at 100 percent, then the situation is twisted around - the 4 core cpu can show it's full potential and it will pay off !!
With the newest build of TG2 and my Q6600 at 2.4 Ghz each of the 4 cores (no overclocking), 6 GB RAM, Vista Ultimate 64bit SP1, the calculation time in the tg2bench-test was 1 minute and 22 seconds. If you check the listing at
http://tg2bench.kk3d.de/ you can tell, this is way faster then an overclocked Q6600 with the older build version of TG2 !!
And you won't reach such a rendering result with a 2 core - even the fastest 2 core can't compete !
What helps even more with those 3D programs nowadays, is for sure the use of 64bit operating system, because the pipeline got a much higher bandwidth to send/receive data and can use a lot more RAM than a 32bit operating system.
Here one more link to a conclusion from a test at
tomshardware.com - which compared 2 and 4 core cpu's in different situations and the conclusion tells the story:
http://www.tomshardware.com/reviews/PARALLEL-PROCESSING,1700-8.htmlIf you want the fastest rendering times, get a 4 core - if you want the fastest gameplay right now (until all the newest games in the future will definitely use 4 cores and more) still get a fast 2 core. If you want a good mix of both, i believe a 4 core stays the winner !