Another reason that chips in phones, whether it is cpu or gpu, are under-clocked is a design choice. Almost every smartphone uses an underclocked chipset. That is due to the properties of cpu designs. A cpu (or gpu) that has a native clock of 1GHz will use MORE power than a chip with a native clock of 1.2-1.4GHz underclocked to 1GHz. So, phone companies design their chips with a native clock higher than their phones will need, then under-clock them to the proper speed. As an example, the iPhone 4 (I know, its a bad-word around here, I'm over it) has a 1GHz processor that is underclocked to 800MHz, and Samsung does the same with their phones. It is all in the name of maximizing the speed while minimizing battery use, and, as was mentioned a few posts back, if their are a few chips that can't meet the 1.2-1.4GHz quality control, they may still be able to be used underclocked to 1GHz, so that means more chips pass final qc, and saves Samsung some money.
There simple rule. cpu can make almost every MHz..... but it depend of
+ Voltage
+ Load
+ Temperature
phone is mobile device with out cooling and free sunbathe.... And there is no module inside processor to controll MHz when power consumption or temperature go higher.... Sandy Bridge control MHz depend of TDP
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TDP (maximal power consumption) depend of MHz/(voltage*current)^2, and OFC load.... Voltage depend of technological process (I mean same size, but different manufacture), some got voltage 2V and current 1A, some got 1V with current 2A
So if you make 200MHz chip and with same performance but clocked 400MHz.... it will take two times more power if there is same Voltage....
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So let's make it simple. If you got game... will you see differance 50-> 60FPS?
Sure not... but to make 60FPS GPU will have to be clocked with 300MHz sure with higher Voltage. God bless FPS cap (that fraking moders taking off).
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Galaxy S got the most powerfull GPU at his times... And GPU is not ussually bottle neck......
ARM is the worst processor with so big mass production.... CPU generate geometry, and transfer it to GPU all the time.... So performance of GPU depend of CPU.....
SGS got same config as some Intel's atom. They got same GPU@400/300MHz.... See how good graphics they can handle on Windows.... But Atom is much more powerfull processor.
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Why Samsung didn't put SGX535? becouse .... what I can see, more transistors you put underclocked better powerconsumption/ per FPS you get... So better SGX540 at 200MHz than SGX535 at 250MHz.....
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There is no burn test on Android, so you can't make stability test. Samsung making this test. There is usually limit about 10-30% just for stability reason for burn tests...
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One mote thing you can overclock GPU only by bus. So overclocking GPU will overclock CPU, but... USB controller, video decoder too. So sometimes you got 20% of GPU limit, but when you whatch movie you will destroy video decoder.