PSU question

[healthandwealth]

Hey there ppl,

I bought a kill a watt meter to see how much kWh my computer pulls from the outlet.  I'm getting a low reading of 115w.  Is that normal?  My monitor, pc, and speakers are all plugged in and that's all the wall draw I'm getting.

I have a single 750w PSU for my computer and two 660 ti GPUs.  Is it normal to read such a low kWh draw?  Or am I confusing what the PSU provides and what I'm actually using?  I was expecting around 600w of usage taking in all the parts and such.

If someone could explain what I'm not understanding here that'd be cool.  I was thinking of building a mining rig or two but wanted to get a handle on how much kWh a rig would use from the wall.  When I'm not reading much on mine it has me a bit confused.

Thanks.

[ning]

Are they (the GPUs) running at full throttle?

[welyoe]

750W means you can use that value at maximum power (if it is a good PSU  ). when you use your computer for ordinary job 115W is common.

use it for mining and it will increase a lot because your GPU will work at maximum speed. try it and you will see.

 

[healthandwealth]

115w was at idle speed.

With cudaminer working I'm getting 405w pull read from Kill a Watt with:

GPU1: Gigabyte 660 ti
99% power
No overclocking

GPU2: Asus OC 660 ti
108% power
Core Clock +125
Memory Clock +350

Guess I've got room to spare.  Anyone ever adjust the Core Voltage when overclocking?  I've never used it.

Now I was planning on building a seperate mining rig with 4xR9 280x OR 4xR9 290's.

Anyone have suggestions on the PSU wattage I'd need for that?  
My guess is 4x250w for GPUs + 150w for mobo,etc = 1250/1300w?

[welyoe]

for 4 x R9 280X a 1250W PSU should be enough ...
use BAMT on a flashdisk or SSD, it will decrease the consumption wattage for your mainboard ...

[healthandwealth]

Ok cool.  I've thought about using Linux to save some money over using Windows 8.1.  Is there much of a difference in hashrate with GUIminer/BAMT vs. Cgminer on Windows 8.1?

[welyoe]

Ok cool.  I've thought about using Linux to save some money over using Windows 8.1.  Is there much of a difference in hashrate with GUIminer/BAMT vs. Cgminer on Windows 8.1?

No. There's no much different.