Re: [gentoo-user] Re: new machine : case + power

[Volker Armin Hemmann]

Am 24.09.2015 um 18:12 schrieb Alan McKinnon:
> On 24/09/2015 16:00, Volker Armin Hemmann wrote:
>> Am 17.09.2015 um 05:38 schrieb james:
>>> Philip Webb <purslow <at> ca.inter.net> writes:
>>>
>>>
>>>>   150914 CPU : AMD X8 FX8370E 8-core 4,3 GHz 16 MB 32 nm 95 W
>>>  I have 3) FX8350. Outstanding performance for the cost. Love them all.
>>>
>>>
>>>
>>>>   150914 Mobo : Gigabyte GA-970A-UD3P 970+SB950 DDR3 2000      :  119.99
>>>>           2x PCI-Express x16 GLAN 6xSATA 6.0 Gb/s 4xUSB 3.0 14xUSB 2.0
>>> I have (3) of the Ggiabyte 990A-UD3P mobos:: I love mine
>>>
>>> Very extensive wiring needs, plus you have to match the video card
>>> power needs to the power supply. None of my older PS would fit the bill.
>>> Also, there has been a quiet revolution in power supply. The efficiency
>>> of the switching circuits will save you more money in the long run
>>> and those electronics will deliver the cleanest power to your other
>>> electronics. PS have ratings so look at the efficiency and oversizing a bit
>>> from calculated loads is never a bad idea.
>>> I would recommend to 'not go cheap' on the PS. Becuase
>>> 4+ GHz can create some very localized heats, I put a 'water cooler'
>>> on the chip that has hoses running to a radiaor bolted on the the main rear
>>> fan of the Case. A wise investment at 4.3GHz. Air cooled CPUs are suspect
>>> at those frequencies, particular if you like to compile  lots of code
>>> or stress the all the cores at the same time.
>>>
>>>
>>>
>>>
>>>>   150914 Memory : Kingston HyperX Fury 8 GB DDR3 1866 MHz CL10 :   68.99
>>> I always max ram in lieu of SSD. I know you have a budget but max
>>> ram is the single biggest item on performance and most things are
>>> memory constrained on processing, ymmv.
>>>
>>> Every thing else look for bargains. Newegg is a great place to vett prices.
>>>
>>> Make sure your case has a big and quite fan to draw air across the HD. Most
>>> new cases do. In all you buy, check the dB (sound level) especially if
>>> you want a quite rig to sit near you. Make sure the UPS you have is
>>> adequate and tested. Put a large light on the UPS. Yank the power cord
>>> of the UPS to the wall and you should not see a flicker nor deeming
>>> of the light of the bulb; thats a good UPS. UPS protects ALL your
>>> electronics, but never printers as their power draw surges can easily
>>> fry a smaller UPS.
>>>
>>> hth,
>>> James
>>>
>>>
>>>
>>>
>>>
>> I have a 125w CPU and a R7 370 plus a shitload of HDDs and all those are
>> quite happily fed by a 450W PSU. A pretty old 450W BeQuiet PSU.
>>
>> Go figure.
>>
>> What does my 600VA UPS says about this?
>> 27% load at the moment.
>
> That's all as expected. There's also this thing we called headroom:
>
> As I said in an earlier mail, and got an earful for my trouble, a 125W
> CPU does not draw 125W all the time and your 450W psu does not deliver
> 450W all the time. Your PSU is delivering about 125W or so average which
> is what I expect from that hardware.
>
> But computers are not nice well behaved LED bulbs that draw constant
> power that never varies. The CPU ramps up to full S1 state, hard drives
> spin up and that causes power draw to surge and spike. How much does it
> need? Hard to give a definite answer but easily 5 or 6 times the
> average, especially spinning up drives that spun down. You can see these
> spikes on lab power meters, ones with screens and graphs. That's what
> the headroom is for - how much extra power can be delivered in very
> brief spikes (<100ms or so) when the hardware really needs it?
>
> If the PSU is weak in this area and can't deliver the full power, the
> load will still try to draw the current, and the voltage must drop to
> compensate. Simple physics. Either way, your 450W PSU might not be up to
> the job when push really comes to shove for your hardware.
>
>

a) I know what happens if you have a bad PSU. That is why I am using
BeQuiet.

b) those 27% include the monitor and router.

b) I know how much my computer draws at full load. 300W. Absolut
maximum. All inclusive. Screen, fritzbox, powered usb hubs, computer
itself. 3