+12V RAIL on psu

[rajsaha001]

when playing games i notice sometimes that the screen freezes momentarily. to check if there is a voltage fluctuation i used a hw monitor and noticed that a ripple is caused IN THE +12V rail during the moment the screen freezes. is this normal or is the psu harming my components??pls help

I mean are ripples in 12 v graph acceptable???
http://s9.postimg.org/crbbzo02n/12v.jpg

 

[rajsaha001]

It is not ripple. It is voltage fluctuations. And it is fine (acceptable). Only oscilloscope can show you voltage ripple...

So, the screen freezes, are they normal or are they just happening to me. The screen freezes only for a fraction of a second.

 

[rajsaha001]

I don't know what causes your computer to freeze. I am just saying that that voltage looks fine.

So, this kind of fluctuation is normal?

 

[rajsaha001]

Yes, and it is only like 250 mV. The components are not powered from those voltages directly. There are DC-DC converters (on the motherboard, graphic card and so on) that takes that voltage and convert them to, for example, 1,8 V for povering RAM. Those DC-DC converters are designed to provide stable and low ripple voltages, and they can take wide ranges of voltages in the input, so even if the 12V rail provides 9 Vor 15V, the RAM will get 1,8 V.

Thanks, that clears a lot. Only out of curiosity, then what difference makes a branded psu from a generic one?

 

[rajsaha001]

Those generic ones have bollocks specs. They claim maximum output power of 500W, but even at 250W load the voltages go out of the tolerances (they drop, a lot, for example from 12V to 7V). Sure, computer should be stilll able to work, but if you increase the load even more voltages vill drop so low that it is imposible for DC-DC converter to provide required voltages to components. So, it is not the problem that PSU is "no name", the problem is that the PSU does not meet to it's clamed specifications.

does connecting a ups help in causing less ripple??????? how are these ripples and noise created then. i learnt that these ripples if goes beyond the limit can harm compnents of the pc.

 

[rajsaha001]

No, UPS does not affect that. Ripple is caused by the switching nature of the SMPS (switch mode power supply). Energy is not transferred from input to output continuously (like with linear power supplys). If duty-cycle of the PWM (pulse width modulation) that drives the switching FET is 50%, that means that energy is transferred from input to output only 50% of the time (capacitor charging). Rest of the energy is stored in the coil and capacitor, and that energy is transferred to the output (from coil and capacitor) in that other 50% of the time (capacitor discharging). But there are losses in the coil and in the capacitor, so less than 100% of energy is transferred. That is the main cause of ripple. Using capacitors of grater capacity and lower ESR (equivalent series resistance) reduces ripple. Using coil of grater inductance increases current capability.
Excess ripple can cause false logic states. Logic 0 is actually voltage that is in the range of 0V to 50% of the Vdd (supply voltage), logic 1 is voltage in the range of 50% of Vdd to 100% of Vdd. So, if CPU runs on 1V, that means that logic 0 is everything below 0,5V. If Vdd ripple is high (200mV, for example) it can increase the logic voltage level. So if you have 0,4V, that is recognised by the CPU as a logic 0, but beacause of 200mV ripple, the peak voltage can be 0,6V and that is recognised as a logic 1 by the CPU. And that means that CPU can not function properly.

since, i have a generic psu i was thinkin of buying the corsair vs 450. will that be okay . i only intend to add a radeon 6670 in the near future. and THANKS for all your detailed answers. i actually learnt a lot!!!!!!!!