Pushing PSU Too Hard?

I was going over the power consumption calculations for my system today and I'm concerned that I might be pushing the PSU too hard.

The FX 3700M card at 100% consumes 75W, the X9000 at 100% consumes 44W, for a total of 119W. The standard power supply for the M570RU-U is only rated for 120W, meaning I only have 1W for everything else, which obviously isn't reasonable nor possible. Considering the overclock I am using for the FX 3700M I can only imagine that with just the CPU & GPU alone I am exceeding the rated capacity of the PSU.

How far past the rating can a PSU be pushed without shortening its lifespan? Has anyone had the PSU for their M570RU-U drop dead from being pushed too far past its rating? Does anyone know a place to get a good deal on a Kill-A-Watt meter so I know how far past the rating I am pushing my PSU?

 

id like to find out too.
but is there any realworld app that will push your systems gpu and cpu to 100% at the same time?

 

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Revising my old posts, 20-25% cannot be sustained over long sessions. 15% over is probably the highest I would go sustained with 20% being the peak maximum for short spikes in power demand to prevent damage from heat to the PSU. An average person's hands can withstand touching a ~60*C until it becomes to scalding hot and pulls his hand away. This of course is touching it when it is already ~60*C and not gradually ramped up to that temperature over time. If your PSU is "too hot to the touch" then it's time to pull back on your overclocks or cool the PSU with a small fan or with a HDD heatsink ontop of it. Fanless PSU's generally have a safe operation of 0-40*C with the upper range extending up to 50*C before power starts to become unstable. Your mileage may vary; quality control comes into play. When in doubt, buy a bigger PSU.

A real manly system wide PSU test is different with each individual person. Only he would know what his system can take or cannot take. But I can tell you that you're never going to touch 44W on your X9000 or 75W on your FX 3700M in any non-synthetic test. And yes, hardware monitors will not give you the pinpoint accurate output reading for power, so don't rely on those. I also doubt that your PSU will die on your before your CPU or GPU. Even if your PSU does die, it's the cheapest component to replace out of the three. You can easily pick up another one for ~$30. There hasn't been a single person on an English forum that had their PSU die on a factory tuned M570xU. But for plain brute force testing to discover the upper limit of a system is vested in maxing out every component on the notebook (ie. the obvious ones, backlight brightness, HDD, ODD, wireless, battery, ports, etc.) At this point, no M570xU or W8x0CU would make it past the least 100 seconds even with a 180W PSU as the bottleneck would be at the power board on the motherboard. The MOSFET's would light up like Christmas trees.

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Hi Soviet Sunrise

I have to disagree with you on this one.

A 3700M could easily reach 75W figures sustained, with OC even 100W peak. The line of work of a GPU is quite diferent from a CPU.

Nowadays such GPUs as the ones based on G92 core are more prompt to limiting, wich means that on the system, there is a high probability that over the CPU and memory subsystem, the GPU is the one holding it back. All it's needed is a recent 3D game.

And if the game it's not demanding enough, turn on some AA, Ambient Oclusion, Transparency Multissampling, and the processed data rises massively.

So it's more likely that on normal situations the 3700M reach it's limits often.

We even need to take in consideration the eficiency of the power adaptor, wich considering a good value could reach 80% of those 120W sustained(20% is transformed in heat and dissipated).

That means only 96W, and this does not stop here. The 20V that the adaptor provides need to be lowered on the motherboard to computer standard voltages(VCore, 3.3 and 5). Again there is an eficiency on how well the MOSFETs and rectifier diodes can regulate the voltage with minimal thermal leak.

About the adaptor temperatures, normal MOSFET operation juntion temperatures reach 120ºC. Rectifier diodes, such as the BAV99s used on the M570RU board have an Tj 150ºC. Tantalum capacitors around 120ºC.

The only problem is some electrolytic capacitors used on the power adaptor

Side by side with the CPU and GPU, the inverter/CCFL light eat quite a few watts too.

The low internal voltages dimish the amplitude of eventual voltage drops and ripple, but the lack of current is there.

An adaptor with an higher current could improve both overcocking hability and stability. The regulators on the motherboard can handle a few amps more, in exchange with a little more heat.

 

I need to respond to a few of your points.

When you mention the figure of 96W left that is not correct. The power supplies ratings take into consideration the efficiency of the supply in the rating. Typical power supplies can exceed their rating at up to 10%, and have current limiting that would would kick in once you exceed that max anyway by shutting down.

You also mention the adapter temps, if properly designed the actual temp the adapter should reach would be limited at a temperature lower than the the lowest specified component, to give some margin. This would be based on typical ambient temps the supply would be subject to.

Electrolytic capacitors can be designed in that have max temps up to 150 C so they are not necessarily the weak link in the supply.

 

i smoked 3x psu's on my good o'le m1710... dang overVolting.. heh.

just purchased a x7200.. can't wait to see what it's got

 

No problem

Efficiency it's not a fixed value, it depends on the load, heat and conditions of the input voltage. A PSU can deliver 80%(typical load situation - 50%) with a deviation of -10% across it's range of load.

Efficiency, like the power factor, is referred independently from the tension and current.

Electrolytic capacitors used for this kind of circuits are only certified to run around 85ºC max. High duty electrolytic capacitors don't exist in 150ºC form because of its unreliability and dielectric breakdown.