Re: Power supply sizing for a new Athlon X2 2700 system
- From: "Lil' Dave" <spamyourself@xxxxxxxxx>
- Date: Sat, 7 Feb 2009 00:54:10 -0600
"Al Dykes" <adykes@xxxxxxxxx> wrote in message
news:gmg4ft$8t4$1@xxxxxxxxxxxxxxxxxxx
In article <gmg43o$7up$1@xxxxxxxxxxxxxxxxxxx>, Paul <nospam@xxxxxxxxxx>
wrote:
Al Dykes wrote:
I haven't built a system from scratch for years. I want a "better"
desktop system for Photoshop and to run VMware VMs for servers that
are modest by today's hardware speeds. No games, no heavy 3d. I know
that 4GB memory is enough for what I do.
In addition to the mobo, I plan on
up to 3 SATA drives,
a Blue-Ray
a CD/DVD burner.
A couple fans.
Is this an approprate PSU? Any other comments are welcome.
PSU: Antec earthwatts EA500 500W ATX12V v2.0 SLI Certified CrossFire
Ready
http://www.newegg.com/Product/Product.aspx?Item=N82E16817371007&Tpk=Earthwatts%20500W
CPU: AMD Athlon 64 X2 7750 Kuma 2.7GHz 2 x 512KB L2 Cache 2MB L3 Cache
Socket AM2+ 95W
http://www.newegg.com/Product/Product.aspx?Item=N82E16819103300
MOBO: ASUS M3A78-T AM2+/AM2 AMD 790GX HDMI ATX AMD Motherboard - Retail
http://www.newegg.com/Product/Product.aspx?Item=N82E16813131331
MEMORY Memory (4 GB total)
OCZ OCZ2RPR10662GK 2gb kit (1gb x 2) pc2-8500 1066mhz 5-5-5-15
240-pin ddr2
VIDEO: on-board video with option to put one mid-range Video card in
without stressing the PSU.
Thanks.
High end video would be 265W. A mid range card (55nm technology), might be
about 80W or so. So what you eventually decide to buy will make a
difference.
3 SATA drives 5V @ 1A + 12V @ 0.6A, roughly 36W
For Bluray, I found a picture of the label on the product, and I
think it says 5V @ 1.9A and 12V @ 3A. A previous number I had in
mind was 12V @ 2.5A.
http://www.cdrlabs.com/Reviews/lg-ggw-h20l-super-multi-blue-blu-ray-disc-rewriter-hd-dvd-rom/All-Pages.html
For CD/DVD, I use 5V @ 1.5A and 12V @ 1.5A. I've measured my
CDRW at 12V @ 1A with media inserted and spinning.
For fans, I allocate 12V @ 0.5A, but you can read the numbers off
the fan hub to be sure.
For motherboard and memory combined, I allocate 50W, coming from the
lower voltage rails (3.3V or 5V). Usually the 3.3V and 5V rails on the
supply are not a limiting factor.
*******
12V2 - powers the CPU. 95W/0.90 = 105.6W, 105.6W/12V = 8.8A of 17A
available.
(The 0.9 factor is 90% conversion efficiency on Vcore.)
12V1 - powers everything else 12V related. I set the CD/DVD to 0.0A
in the following, because if you're using the Blu-ray, then
the CD/DVD tray is probably empty.
80W_video/12V + 3*0.6A + 3A + 0.0A + 0.5A = 6.7+1.8+3.0+1.5+0.5= 12.0A of
17A available
System power estimate (includes the 5V things not counted yet, includes
5V @ 2A for 5VSB standby).
(all 12V loads) 12V * (8.8A + 12.0A) = 249.6W
mobo+RAM 50W 50.0W
SATA_5V 3*5W = 15.0W
Blu-ray_5V 5V*1.9A = 9.5W
CD/DVD_5V 5V*1.5A = 7.5W
+5VSB (USB/WOL) 10W = 10.0W
--------------- ------
Total 341.6W
So your new supply looks good. Even with my bloated estimates.
You supply passes on the 12V1 and 12V2 calculation, and also on
total power. And your 3.3V/5V are not likely to tax the supply
limits - I cannot provide a precise way of working that out,
and my 50W estimate is based on measuring a couple motherboards
here. That is the best I can do.
Thanks. I ran just ran it thru the Antec estimator and came up with a
little more, but not much.
--
Al Dykes
News is something someone wants to suppress, everything else is
advertising.
- Lord Northcliffe, publisher of the Daily Mail
Ignore the total wattage as the guide for the power supply. Rather, group
each voltage leg by total amps required for the entire PC. Add some cushion
for add-ons, and 20% for degradation. Then, go shopping for the power
supply based on those voltage leg amp requirements. You may be surprised in
the variety of higher total wattage power supplies that don't meet your
needs. And, lower wattage power supplies that do.
If the data is not available for a power supply regarding each voltage leg
amperage, don't buy it.
--
Dave
.
- References:
- Power supply sizing for a new Athlon X2 2700 system
- From: Al Dykes
- Re: Power supply sizing for a new Athlon X2 2700 system
- From: Paul
- Re: Power supply sizing for a new Athlon X2 2700 system
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