Real Power Consumption - 4870 X2 & GTX295 out of Spec!

[Chruschef]

i don't get why this is such a big deal...

GPU's have to power an entire circuit board, RAM, GPU. GPU cores also designed to handle more heatload, than fragile CPU's so it isn't the same as a "high-TDP" processor... though, these recent GPU's are quite power hungry.

[largon]

[IMG]http://ht4u.net/images/reviews/2009/power_consumption_graphics//4870_wandler_3.png[/IMG]

Now it is no supprise anymore, why AMD lowers the load synthetically. The card simply can not not bear the load FurMark creates. While the GPU-Temperature is absolutely uncritical, the voltage regulator temperature is not. Meanwhile the datasheet of the voltage regulator is available and Vitec specifies the temperature to 125 degrees.

Via FurMark we reached within a few minutes temperatures from about 125 degrees. Thus we can say: The Radeon HD 4870 definitly has a problem with its voltage regulators when using FurMark. Surely FurMark is a worst-case-scenario, but it points out that the voltage regulators on the Radeon HD 4870 work near its maximum specification.

http://ht4u.net/reviews/2009/power_consumption_graphics/index8.php

That "max 125°C specification" applies only to the Vitec 59PR9853 multiphase inductor. The actual voltage regulators which the "VRM phase [number] temperature" -figures in Rivatuner come from are the Volterra VT1165SF chips - and their max specified operating temp is unknown (datasheet is not public). My point being, those Vitec inductors should run cooler than the Volterra chips since the coil surely consumes only some minute amount of energy (~5W), and as such their temps must be lower than the 120-125°C of the Volterra's which generate a considerably higher amount of heat.

[Kylian]

hey kylian, nice to have you on xs

i remember that furmark heats up gpus more than anything else, but im quite surprised that its supposed to heat up high end cards almost 100W more than games?

Have a look on it in a procentual way. Difference between 3DMark06 and FurMark are about 20-30%. If you keep in mind, that even many games are causing a notably higher power consumption than 3DMark06, those values aren´t to high anymore IMHO. But you still need to handle FurMark as an worst-case-scenario, though. If you don´t believe it, just check it your self, get FurMark and start some little testing .

The issue is that FurMark is still quite CPU bound, even at the higher settings.

Sorry, but this is one more time simply not true. We had look at this, and tested Power Consumption on 4870 X2 with different CPU-clock-Speeds (1,8 vs 2,6 GHz). The differences in Power Consumption had been in the range of meassuring tolerance.

That "max 125°C specification" applies only to the Vitec 59PR9853 multiphase inductor. The actual voltage regulators which the "VRM phase [number] temperature" -figures in Rivatuner come from are the Volterra VT1165SF chips - and their max specified operating temp is unknown (datasheet is not public). My point being, those Vitec inductors should run cooler than the Volterra chips since the coil surely consumes only some minute amount of energy (~5W), and as such their temps must be lower than the 120-125°C of the Volterra's which generate a considerably higher amount of heat.

But this one is really true. We updated the page accordingly. Thanks a lot for your hint, largon.

Greetings,
Leander - HT4U

[Manicdan]

If you don´t believe it, just check it your self, get FurMark and start some little testing .

did you imply that i should fry my computer? i hope not

[Kylian]

Nah, you won´t kill your card just with little testing with FurMark. There´s no need to run FurMark for long time, just to see that it causes a much higher Power Consumption than 3DMark06.

[SKYMTL]

Sorry, but this is one more time simply not true. We had look at this, and tested Power Consumption on 4870 X2 with different CPU-clock-Speeds (1,8 vs 2,6 GHz). The differences in Power Consumption had been in the range of meassuring tolerance.

Try a HD 4870. At high res you shoud see between 20-25% CPU utilization on a quad core. If not, please post your FurMark settings since I have yet to see a single GPU card not post high CPU utilization in FurMark.

[Kylian]

Sorry, but i don´t get your point. You reffer to a CPU-Utilization from about 20-25%. So where is the problem? As long as CPU-Utilization is as low as you stated, CPU-Perfomance shouldn´t have any influence to our measurements since it is simply no bottleneck. And we additionally confirmed this with our meassurments at different cpu-clocks.

Greetings,
Leander - HT4U