i7 900X4C or i5 900X4D

I asking this question to John or anybody who has both models.
I am in position to sell my 900x3c and buy short used i7 900X4C-with Croatian keys or new i5 900X4D-K01DE.
The most important thing for me is battery life ,so if i7 drains battery much faster i would go with i5 .if its difference only 15 minutes then i go with i7 with Croatian keyboard.
So John can you please tell me whats the difference in battery life,can you please please make some kind of test ,like charge them full (or 80%)and then open long Youtube video with maximum brightness and read how much battery have left while its playing.You dont have to do that today i have 5 days to decide.
Thanks in advance i hope i dont ask to much from you.
(dinner when you visit Hvar ,i hope you dont count that like bribe here on notebookforum)

update:it came to my mind we can read current power consumption in "Easy Settings" ,maybe to start video and see how much W it uses.

 

A quick test using wPrime to load the CPU and HWiNFO to monitor the power drain while running on battery. Both displays on similar brightness

X4C with i5-3317U
CPU @ 800MHz (power-saving mode) total power drain ~11.5W
CPU @ 1.5GHz (maximum non-turbo speed), total power drain ~ 15W

X4C with i5-3537U
CPU @ 800MHz (power-saving mode) total power drain ~11.5W
CPU @ 2.0GHz (maximum non-turbo speed), total power drain ~ 16-17W

These results show that at the minimum CPU speed then the power consumption is similar, while at the maximum non-turbo speed (ie using the Samsung Optimized power plan when on battery), my i7 CPU uses 15% to 20% more power but is running 33% faster than the i5 so it is more power efficient and can complete a finite task faster (but if the task is infinite then it will drain the battery faster).

I would also note that the maximum power consumption of the i7 CPU under full load in turbo mode (actual speed 2.9GHz) is higher than the i5 (actual speed 2.4 Ghz). However, the extra heat of the i7 under sustained full load results in higher temperatures and more fan noise (I encountered some thermal throttling until I repasted the cooling system). In that respect I prefer the slower but quieter i5 machine. A slower i7 than my 3537U may not run as hot while the i5-3337 may run slight warmer under full load than the 3317U.

Is the price or the keyboard difference also a factor in the decision? I note that the Croatian models have a 256GB SSD so the need to do an SSD upgrade will be less.

John

 

Thanks John ,you are great person.
I have desktop for heavy use and i only use laptop for emails and surfing,so it seems that for me they will have same battery life.
i5 900X4D-K01DE is model from Amazon.de that costs 1000€ and i7 900X4C is used model that costs 1200€ .He says he didn't use it at all because he bought 900X3E at same time and he liked 13.3" more.Only thing that bothers me is ,that this new i5 models are not same quality like those with i5-3317 ,dont ask me why ,i just have that feeling.
If i buy i7 model i will have most important thing for me,shell of notebook with Croatian keyboard and 256gb SSD.If notebook dies at some point i can always buy model from amazon.de(900x4d-k01de) and put his internal components(motherboard,battery,etc..) into old 900X4C.Of course if it has same position of screws that holds motherboard and everything else in the place.
If i buy i5 model i will not sell my 900X3C because then i need Croatian keys(š,đ,č,ć,ž from it.I want to move keys to new i5(900X4D-K01DE) model.I hope it is possible to do that.If they sell replacement keys on web for Series 9 then it should be possible to do exchange.
What you think about this crazy plans (you dont have to answer this )
Anyway ,thank for results and if you ever come to Hvar please call me.

 

I would vote for the notebook with the Croatian keyboard and avoid the possible risk in breaking something while trying to swap the keycaps and the intact X3C will be easier to sell.

John