Calculating PSU

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with the following components:  1
ASUS F1A75-M pro m/b (BIOS 2206) , AMD Llano A6-3650 boxed, 4*4096MB
(16GB) KHX1600C9D3/4GX,
Asus EAH5670 512MB,
HDs: 500GB+640GB (Samsung HD103UJ, Samsung HD154UI SATA-HDs)
WT KM06 case(3*5.25", 2*3.5" ext, 3*3.5" int), add'l Nexus 80mm case
fan, Antec Basiq430W
and an el cheapo USB3 card from

the calculator says the needed PSU would be something on the order of 460W +
(minimum 461W, recommended 511W )
But I have only the 430W Antec Basiq (about 2years old)   and the
machine still working (apart from the sporadious tearing on the monitors
lower left corner, which was in another post)

If I now upgrade my GPU to a Asus GTX650-DC-1GD5 NVIDIA GeForce GTX650
1024 MB ,
do I HAVE to upgrade the PSU, and If so, how high??

1)    1 phys. CPU, regular MB, CPU=AMD, FM1, A6-3650, CPU util=100%, stock
clock, Video=AMD Radeon HD 5670, 2 regular SATAs, 1 DVD-RW,
1 BlueRay BD-RE (about to upgrade later), No PCI cards, 1 PCI-e 1x,
External device=4(sporadically), 1 80mm fan, System load 100% (running
BOINC), Capacitor aging I set at 50% as the PSU is old
Thomas Wendell
Helsinki, Finland
Translation to/from FI/SWE not always accurate

Re: Calculating PSU

tumppiw wrote:
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A6-3650 = 100W, 100W/12V * 1/0.90 eff = 12V @ 9.26 amps or 111.1 watts at supply.

Motherboard - allocate 50W, with some split between 3.3V and 5V loading. This
is intended to cover four DIMMs at 2W each as well. 50W is supposed to
cover any chipset power requirements.

Hard drive estimate - 12V @ 0.6A, 5V @ 1A, about 12W total. Some drives
are as good as 5W. I use 12W for an estimate.

Optical drive - 12V @ 1.5A, 5V @ 1.5A. 25.5W total. The one drive I've
measured, drew 12V @ 1.0A while the media was spinning.

Fans - power is stated on fan hub, but I allocate 12V @ 0.5A total or 6W.

HD5670 video = 28.7W during 3D game play. 12V @ 2.2A, 0.7W on 3.3V rail

Allocate 10W for USB on 5VSB plus other loads on motherboard.

Antec Basiq 430W ?$S640W$

    3.3V @ 20A, 5V @ 20A,  Total for two outputs less than 115W
    12V @ 17A, 12V @ 16A,  Total for two 12V outputs less than 384W
    -12V @ 0.8A
    5VSB @ 2.5A
    Total PSU power less than 430W

Not all outputs can go to the maximum value at the same time.

Totals (and compare totals to Basiq ratings)

First, work out 12V amps.
12V2 = 9.26 amps, as only the processor is on 12V2     (and is < 16A)
12V1 = 2*0.6 + 2*1.5 + 0.5 + 2.2 for video = 6.9 amps  (and is < 17A)
3.3&5V = 50W + 2*5W + 2*7.5W + 0.7W video on 3.3 rail = 75.7W (and is < 115W)
10W for USB

The 12V amps are within limits, as are the lower rails.

Now work out total power.

Total power = 12*(9.26 + 6.9) + 75.7 + 10 = 279.6 watts (and is < 430W)

The GTX 650 is listed as "64W max" here. The figures on this site
are from the manufacturer. Whereas, the Xbitlabs figures are measured
from a single test unit. The 3 sigma of chip power could fall a lot
higher than a single measured unit, yet I feel the Xbitlabs single
measurement is a better indicator for most users. In any case,
64W minus 28.7W is an extra 35.3W or approx 12V @ 3A on 12V1.

If we change the video card from HD5670 to GTX650...

The new total power is 279.6 + 35.3 = 314.9W
The 12V1 current is 6.9 + 3 = 9.9 amps (and is < 17A)

The Basiq is comfortably loaded (73%), and does not need to be replaced.
Only if there were signs the Basiq was failing, would I change it.

The 0.9eff is a 90% efficiency factor for VCore conversion. It is
included as a factor, to show some contribution from heating in the
VCore regulator MOSFETs and coils, and driver chips. The actual figure
might be worse than that by a bit, but isn't going to change the results.

I see scrolling back, one of the optical drives is Bluray. Some
of those have a higher power rating, so that might mean another
12W and an additional 1 ampere on 12V1. Power might be highest
while burning, while movie playback will be less than the
pessimistic max. Numbers still look good.

If the power supply calculator site is including "capacitor aging",
personally, I would pretend the Basiq is brand new and 100% functional,
and use your own judgment as to whether it's "old" or not. Perhaps
by removing capacitor aging, a more reasonable power number
will result ?

While I have the equipment to measure real systems here, as
a home user, I don't upgrade often enough to have a ready
supply of actually measured figures. I can tell you, for
my Intel processors (65W units), they no longer draw 65W.
One draws 36W, the other 43W. The AMD processors might be
closer to their TDP values. Actual power could always be
less than the TDP value. On older generation processors,
I was finding measured power was equal to TDP value, so
manufactured processors are doing better now, than the TDP
value, in my limited measurements. Something like Prescott
or Northwood era, the power was likely to be closer to
the estimated value, or even a watt or two higher.


Re: Calculating PSU

On 4.11.2012 11:36, Paul wrote:
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Thanks, will test without upgrading the PSU
(in maybe 2-3 weeks)

Thomas Wendell
Helsinki, Finland
Translation to/from FI/SWE not always accurate

Re: Calculating PSU

4.11.2012 11:36, Paul kirjoitti:
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I finally got around to updating my system. I excahnged the GPU to from  
my old Asus HD5670 to a Asus HD7790, and it works. With both CPU and GPU  
running at 100% (mining bitcoins with both to get them fully utilized)  
my el cheapo Kill-A-Watt says my computer is using 210-250W of power

Thomas Wendell
Helsinki, Finland
Translation to/from FI/SWE not always accurate

Re: Calculating PSU

tumppiw wrote:

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These days, the GPU seems to be the most sensitive component to PSU
output, since it is often the highest power-consuming component in the

Your current GPU tops out at around 30 Watts, but the GTX650 is around
110 Watts.  While the 430 Watt PSU is fine for now, I would upgrade to
a GOOD 500-650 Watt PSU if you're going to upgrade GPUs.  You can stick
to the low end if you don't plan further upgrades in this case, but go
higher if you think you might get a bigger GPU one of these days.

A Kill-a-Watt meter or a UPS with an output display can tell you what
your system is pulling, so you can gauge better from there...

Re: Calculating PSU


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Have a look for this thread Power Supply Calculators in this news
group :uk.comp.homebuilt.

I started it on Jan 16th this year

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