Well this was a bit of a shocker to me after reading some of the posts in here about power consumption.
I measured the AC power draw on my new bench setup... (excuse the mess)
It includes the following:
- DFI NF680i LT
- X3220 OC'd to 3.6GHz at 1.55V
- Single SATA HD and SATA Optical Drive
- DDC-2 Pump
- 4x120mm Fans
- Corsair 520W PSU
For graphics cards, I have an old POS MX4000 PCI card (seen lying on the anti-static mat above) and my recently purchased volt modded 8800GTX (installed in the pic above). I tried the power draw with both cards as you can see below.
I also tested the power consumption of my 2-year old 24/7 AMD X2 system with 7900GS for comparison.
Here is a description of the tests (note I rounded to the nearest 5W):
Boot: The maximum observed power draw while turning the system on and booting Vista. FYI... The maximum draw appears to be when the graphics drivers load in Vista after the scrolling progress bars disappear.
Idle: This is the draw after Vista has booted and all HD activity has stopped.
Sm FFT: This is loading all cores (2 on the AMD System and 4 on the X3220) with PRIME 25.2 Small FFT. Max power draw remains steady and doesn't fluctuate at all during this test.
+3DM06: While continuing to run PRIME in the background, I launched 3DM06. The max power draw I observed was during the initial graphics sequence where everyone is still in the landing ship. The rest of the time, the power consumption may be lower by 10-20W. I could not run this test on the POS MX4000.
Comments:
- Given that Jonny has measured the efficiency of this Corsair PSU at about 80%, and the peak AC draw with the 8800GTX was 575W, that means the PSU was delivering about 460W DC. That's alot!
- The 8800GTX adds an additional AC draw of 115W (92W DC) over a mundane GPU even when it's not doing ANYTHING. I haven't even started to leverage the volt mods and overclocking much yet. Although I should point out that the BIOS currently on my 8800GTX does not have 2D clock settings so the core and shader are running at full speed which obviuosly increases the power draw during idle.
- Given that the final system will include 4 raptors, an Areca RAID card, an X-Fi, another cooling loop with DDC pump, and misc. lighting, there is no doubt that a 500+W PSU is NOT up to the task.
- While my new quad-core system is at least double (if not triple) the performance of my old AMD system, it doesn't come cheap... It consumes over double the power at load!
- If you are interested in what I used to test... it's a simple energy meter purchased at Canadian Tire for $25, similar to the Killawatt device that's ubiquitious in the US. It stores the max power and current, includes an overload warning, a feature to set and monitor energy costs and a battery function to maintain collected data even after it's disconnected from the power.
I'm interested in thoughts/comments/etc.
In particular, with respect to the power consumption of a motherboard and GPU as I tested above, I'm curious what % of that load is on the 12V rails vs. the 5V or 3.3V rails. What, if anything uses 5V and 3.3V? The reason I ask is that with a max AC draw of 575W at 80% efficiency, that's 460W DC the PSU is delivering... if that's mostly 12V, then it's close to it's rated maximum of 480W on the 12V rails.
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Originally Posted by Borgod
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