When I was swapping my motherboard in for a different one, I found something interesting. I used my kill-a-watt to measure how much my old motherboard + CPU + memory was using compared to my new (used) one.
The hardware
I swapped out a Pentium D 930 (yes, I know, old hardware, but it served its purpose) with a Core2Duo T5500. Impressive! The motherboards are nothing impressive (read: I forgot the brand and model), and the only thing noting was the difference in memory: from 2 GB to 4 GB. Other than that, they are pretty similar in performance (I measured with 3DMark2006: 6500-ish vs 7100-ish, respectively).
Interesting!
The interesting thing wasn’t the power usage difference between them (well, I expected a drop in power usage and got it), but the difference in power usage when I used a 400 W PSU with the new setup compared to a 500 W PSU. For the record, the only thing I changed was the PSU. No settings changed, no other hardware changed. I didn’t even run windows updates in between them. Unfortunately, I don’t have the numbers for the D930 with the 500W PSU, because I already swapped it for the other motherboard when I thought about trying that.
The details
In the table below you can see power usage that I measured (it was oscillating a bit sometimes (a few percentage of the total), I took a number that looked average). The activities are: Busy (Battlefield: Bad Company 2, ingame), Idle (Windows desktop, no programs running), Windows Standby (as the name implies), Off (shutdown, cable plugged in).
Anyway, the measurements:
| Activity | Pentium D 930 400W | C2D T5500 500W | C2D T5500 400W |
|---|---|---|---|
| Busy | 210 W | 145 W | 120 W |
| Idle | 133 W | 85 W | 69 W |
| Windows Standby | 121 W | 6 W | 4 W |
| Off | 3 W | 6 W | 3 W |
As expected, there is some difference between the Pentium D930 and the C2D T5500 (max 115 W, min 3 W), even forget that the D930 is terrible at being Standby (I mean: 121 W? really?) but look at the difference between the same C2D with a 400 W and 500 W PSU (max 25 W, min 2 W). I guess the 400 W PSU I have is more power efficient. By the way, I rechecked 3DMark2006 for both the 400 W and 500 W PSU, both are around 7100-ish, so no big change there.
Update: 400 W PSU is FSP Group Inc, 500 W PSU is Coolermaster
So the 400(/500)W means that it can use a max of 400W or does it refer to something else?
If the latter, would it then not make sense that the usage of a 500W device is bigger than the usage of a 400W device?
And if they are from different manufacturers, could there not be other design differences in the PSU causing this?
and.. windows?? :)
The 400/500 W is an indication of the peak power that the PSU can deliver (but not how long it can deliver this ;)). I knew different PSU’s have different efficiency levels, but I was surprised how much this was for these two brands. I got this link from @engessa http://gathering.tweakers.net/forum/list_messages/1415679 (Dutch). It explains a lot about PSUs and energy efficiency. Another link I got from @engessa is http://www.80plus.org/manu/psu/psu_join.aspx , a list of manufacturers that get awards for making energy efficient PSUs. In this link you will see that the manufacturer 400 W PSU (FSP Group Inc.) got a lot more awards than the CoolerMaster one. This explains a lot :)
Windows: I use this machine for gaming ;)
On a side note: looking forward to more games coming to the Mac ;)
ok, FSP seems pretty good indeed, most awards, absolute anyway, percentage-wise comparison might be interesting too.
ok :)
check.. that would be good.. but Mac is in general still too expensive in comparison to either windows or ubuntu systems with same specs, imo