What computer is faster, and better over all?

I'm having a hard time deciding on what computer to get, its between a Dell 3000 desktop and a Lenovo 300s desktop. Everything between these two are pretty much similar, they both have 8gb of ram, 1tb of hard drive space, and both use intel i5, the only difference really besides that the Lenovo is a lot smaller is that the Dell is a dual processor up to 3.40 GHz speeds, and the Lenovo is a quad core processor with speeds at 2.9 GHz… So what one is better? Which one would preform the best under pressure from a game, or multiple windows open at the same time? Much help needed asap!

the Lenovo desktop specs http://www.ebay.com/itm/Lenovo-IdeaCentre-300s-Desktop-Intel-Core-i5-8GB-Memory-1TB-HDD-Black-Gray-/321932575619?_trksid=p2141725.m3641.l6368

the Dell desktop specs http://www.staples.com/Dell-3000-Desktop-i3847-10000BK-with-Windows-10/product_1738540

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