My 4870 1GB power consumption numbers

[SSChevy2001]

Originally posted by: Cookie Monster
Thing about the HD4870 and rather high idle power draw can be blamed on the use of GDDR5. With the initial implementation of GDDR5, i dont think AMD took advantage of the "power saving" features of the GDDR5. If you can successfully lower its memory frequencies (not sure about voltage), huge gains can be had for the idle power draw. The only problem is that the current boards in my knowledge, they lack the stability when reduced to a certain memory frequency threshold. So AMDs second implementation of this new memory module will probably be much more refined, i.e include these power saving techniques.

My stock ref 4870 idles just fine at 550/200mhz @ 1.083v. The idle temp is around 43c @ 12% fan speed, which clearly shows that the power consumption has dropped a good deal.

Why ATi didn't using higher load fan settings or better idle clocks is a mystery, but the 4870 has plenty of room to decrease the idle power consumption.

 

[Schmide]

Originally posted by: jamesbond007

I use this power supply, which has an 83% efficiency rating, so 25% would be a bit much to estimate with. Additionally, thilan29 said that the Killawatt meters have troubles with active PFC units, which my PSU is. Perhaps that is what's throwing the numbers off a bit? Is there any real way to measure the power draw?

Also, I'm not sure what the difference my APC unit would make since my meter is between the UPS and my tower.

As for the efficiency, I just threw in a generous number. 80+% is more the norm but I was conservatively fudging.

I was thinking that there may be some frequency variation during high draws when your system is at load. A few Hz and the Killawatt may be seeing more power over less time. Shrink the divisor grow the numerator ya know.

The other way to read power is to use a clamp meter on a hot wire.

 

[jamesbond007]

So, I installed the ASUS PC Probe II this afternoon before I reset my BIOS so that my keyboard would work in a non-Windows environment, like messing with BIOS settings. Anyways, I set my overclock back to 3.2GHz, but I did some research on the voltages. On AUTO, the motherboard was putting out 1.64V to my norhtbridge! Good gravy! I believe somewhere around 1.2V is stock, but since I'm overclocking, I put it to 1.35V manually, which is where most people hitting the 3.2-3.6GHz range with my CPU are using. Additionally, my DRAM voltage was putting out 2.2V on AUTO, so I set that to 2.02V, which I believe G.Skill recommends 2.1V for the 533MHz (1066MHz DDR) spec. I verfied the AUTO settings both before and after the BIOS reset.

So far, everything has run PRIME95 stable for hours and no lockups or issues while gaming. My motherboard temp went from and idle of 64C down to 45C. My NB temp went from a 78C idle to a 56C idle. My CPU is idling at 34C, which use to idle around 60-65C. I don't know what was going on before, but I'm glad all seems to be well now. Just to be safe, I increased my GPU fans to 40% to help keep the ambient temp inside the case much cooler, which I believe is helping my numbers across the board.

As of now, I'm using about 315W idle as I'm typing this and my load temps while playing Crysis hovered between 500-550W using the same Killawatt meter. Yay!