is 1gb enough for gaming in a smartphone?

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It's fairly weak, but might be good enough considering the zenfone 5 is 720p. Higher resolutions are pretty, but they take too much RAM and GPU power to run. 720p seems to currently be the sweet spot for phone gaming, and the PowerVR SGX 544mp2 should keep playable framerates in the majority of games, but it's probably a good idea to check YouTube videos for gameplay just in case.

I don't know exactly how heavy ZenUI is, but when I was considering buying it myself, reviewers typically thought it was pretty light and smooth.
For basic games, yes. For example angry birds. But for more intense games like asphalt 8 no. Your phone will start to lag. Also it is not just about the ram. You should look at the maufacture's skin they put. Some are very heavy like touchwiz and some are light like the moto x's skin.
 
how about EmotionUI? is it heavy?

 
Just like in PCs, most of your framerate is going to be determined by the GPU. 1GB of RAM isn't great, but it's not a big problem if you don't keep other apps open while gaming, as long as you have a decent GPU (Adreno 320 or equivalent/better).
 
is this good? Intel® Atom™ Dual Core Z2560 Processor 1.6Hz with Intel Hyper-Threading and PowerVR SGX544MP2

 
is the ZenUI (Asus) Good? cus going to pick the ZenFone 5 (A501CG)....

 
It's fairly weak, but might be good enough considering the zenfone 5 is 720p. Higher resolutions are pretty, but they take too much RAM and GPU power to run. 720p seems to currently be the sweet spot for phone gaming, and the PowerVR SGX 544mp2 should keep playable framerates in the majority of games, but it's probably a good idea to check YouTube videos for gameplay just in case.

I don't know exactly how heavy ZenUI is, but when I was considering buying it myself, reviewers typically thought it was pretty light and smooth.
 
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