Re: Good PSU choice? CORSAIR CMPSU-650TX 650W ATX12V / EPS12V SLIReadyCrossFire Ready 80 PLUS Certif

Y

Yousuf Khan

Hello.

http://www.newegg.com/Product/Product.aspx?Item=N82E16817139005 -- I
noticed the price is cheap, but is that PSU good to get? NewEgg shows
high ratings. I wonder why so cheap. Bad batch?

This is for my upcoming computer upgrade, over my current primary PC as
shown in http://zimage.com/~ant/antfarm/about/computers.txt , during my
Christmas break:
- Intel i7 950 CPU -- http://ark.intel.com/Product.aspx?id=37150
- Motherboard/Mobo. (GIGABYTE GA-X58A-UD3R [newer] or EVGA X58 FTW3
132-GT-E768-KR [older])
- 6 GB of RAM)

Thank you in advance. :)
Click to expand...

A 650W PSU is hardly top of the line anymore. It's like what a 350W PSU
was about 3+ years ago. These days the high end PSUs are putting out
1000-1200W. So basically, much like processors, what used to be high-end
before is now bargain-basement.

I got a 650W PSU from Zalman myself, about 2 years ago, and I got it for
much the same price, but that was on Ebay.

Yousuf Khan

PS-BTW, I corrected your newsgroup crosspost, it's
"comp.sys.ibm.pc.hardware.chips" not "comp.sys.hardware.ibmpc". :)
 
K

krw

A GPU isn't the only thing that pushes a PSU. Hard drives are another
big draw.
Click to expand...

In usual installations 3-8W per drive isn't going to tax a 500W supply very
hard.
 
B

Bob Willard

In usual installations 3-8W per drive isn't going to tax a 500W supply very
hard.
Click to expand...

A few Watts of steady-state power drain is not much to worry about.
But, for PS sizing, you need to consider the start-up which can be as
much as 3A on the 12V rail per SATA HD. {And, for extremist PCs with
RAID10 or RAID6 sets of 15K RPM SCSI HDs, it gets *really* serious.}
 
K

krw

A few Watts of steady-state power drain is not much to worry about.
But, for PS sizing, you need to consider the start-up which can be as
much as 3A on the 12V rail per SATA HD. {And, for extremist PCs with
RAID10 or RAID6 sets of 15K RPM SCSI HDs, it gets *really* serious.}
Click to expand...

SCSI sequences drives, doesn't it?
 
W

willbill

Do I assume it will be fine for my upcoming system upgrade?
Click to expand...

Depends on what you want the PC to do; e.g. see:

550W Roundup: Three PSUs at Different Prices
by Martin Kaffei on 10/28/2010
http://www.anandtech.com/show/3985/three-550w-psus-for-different-prices

More recently and perhaps less on topic to you, you might also see:
http://www.anandtech.com/show/3992/1000w1200w-highend-psuroundup
( 1000W-1200W Roundup: Five High-End PSUs )

http://www.anandtech.com/show/4011/corsair-ax750-80plus-gold
( Corsair AX750 80 Plus Gold: Putting Corsair's Best to the Test )

Bill
 
D

daytripper

SCSI sequences drives, doesn't it?
Click to expand...

That's a host adapter firmware feature that depends on drive support - but,
yes, it's supported by SCSI, and SAS, and SATA as well. My old SCSI raid tower
used it, and my current SATA array is using it now...

/daytripper
 
D

daytripper

A GPU isn't the only thing that pushes a PSU. Hard drives are another
big draw.

Yousuf Khan
Click to expand...

Not even close. I have an ATI 5970 that will pull almost 300 watts - and can
go from a low-power state to full-on watt-suckage mode in a heartbeat.

The half-dozen 10K rpm hard drives and the SSD barely pull a tenth of that
once they're all spun up. And with the cabinet using sequenced spin-up there's
not much of a "thump" when powering up the drives.

fwiw, Rosewill 1000W continuous 80 plus gold certified modular power supply
with one big fat 12V rail feeding a 980x, that freaky 5970 and a bunch of
storage - and is amazingly quiet doing it...

/daytripper
 
R

Rev.3.20

Hello.
Click to expand...
http://www.newegg.com/Product/Product.aspx?Item=N82E16817139005-- I
noticed the price is cheap, but is that PSU good to get? NewEgg shows
high ratings. I wonder why so cheap. Bad batch?
Click to expand...
This is for my upcoming computer upgrade, over my current primary PC as
shown inhttp://zimage.com/~ant/antfarm/about/computers.txt, during my
Christmas break:
- Intel i7 950 CPU --http://ark.intel.com/Product.aspx?id=37150
- Motherboard/Mobo. (GIGABYTE GA-X58A-UD3R [newer] or EVGA X58 FTW3
132-GT-E768-KR [older])
- 6 GB of RAM)
Click to expand...
Thank you in advance. :)
Click to expand...

A 650W PSU is hardly top of the line anymore. It's like what a 350W PSU
was about 3+ years ago. These days the high end PSUs are putting out
1000-1200W. So basically, much like processors, what used to be high-end
before is now bargain-basement.

I got a 650W PSU from Zalman myself, about 2 years ago, and I got it for
much the same price, but that was on Ebay.

        Yousuf Khan

PS-BTW, I corrected your newsgroup crosspost, it's
"comp.sys.ibm.pc.hardware.chips" not "comp.sys.hardware.ibmpc". :)
Click to expand...

Just a side note for others who may be considering a larger supply.
For those of you building a box or just needing a supply keep in mind
the bigger the supply i.e., the higher the output wattage then
typically the more it costs to operate. If all you need is 350 watts
of output power (typically plenty for business apps.) and you purchase
a 1000+ watt supply then the added capacity is only generating heat
and costing you money to cool and operate.

Too many times people become wrapped around the axle sort of speak
with numbers rather than actual requirements. A general rule of thumb
for capacity is full load plus 125% for spikes and sustained
operation. The same number is used when fusing AC circuits.Some may
feel this is a bit conservative for general supply design but it
provides plenty of overhead.

Remember heat kills electronics. If you don't need the added
horsepower why heat your PC & house with an over sized supply.
<>< Rob
 
W

willbill

Thanks. I will be using my box as a workstation, media center (have
three TV tuners), and gaming. :)
Click to expand...


Given that, you might want to spend more for a low ripple PSU.

e.g. I'm currently building 4 new machines, with primary focus on
using at least a couple of them for high end playback of stereo
music from flac files.

Does low ripple make a difference for this?

I frankly don't know, but have enough suspicion at this point
that it does, which has lead me to buy higher end (more
expensive) PSU units that have lower ripple.

Bill
 
P

personaobscura

Just a side note for others who may be considering a larger supply.
For those of you building a box or just needing a supply keep in mind
the bigger the supply i.e., the higher the output wattage then
typically the more it costs to operate. If all you need is 350 watts
of output power (typically plenty for business apps.) and you purchase
a 1000+ watt supply then the added capacity is only generating heat
and costing you money to cool and operate.

Too many times people become wrapped around the axle sort of speak
with numbers rather than actual requirements. A general rule of thumb
for capacity is full load plus 125% for spikes and sustained
operation. The same number is used when fusing AC circuits.Some may
feel this is a bit conservative for general supply design but it
provides plenty of overhead.

Remember heat kills electronics. If you don't need the added
horsepower why heat your PC & house with an over sized supply.
<>< Rob
Click to expand...

So, you believe that a power supply always puts out its maximum capacity (and
thus its maximum thermal output) regardless of load?

That theory is quite full of rubbish...
 
K

Ken

Just a side note for others who may be considering a larger supply.
For those of you building a box or just needing a supply keep in mind
the bigger the supply i.e., the higher the output wattage then
typically the more it costs to operate. If all you need is 350 watts
of output power (typically plenty for business apps.) and you purchase
a 1000+ watt supply then the added capacity is only generating heat
and costing you money to cool and operate.
Click to expand...

No. That's wrong.
 
K

krw

So, you believe that a power supply always puts out its maximum capacity (and
thus its maximum thermal output) regardless of load?
Click to expand...

Even if both supplies are 90% efficient, the difference in heat output of a
1000W supply over a 350W supply is 185%. Even 65W is a lot of waste heat to
dissipate. The cost difference is trivial but it still is waste heat and more
importantly, at least to me, more noise.
That theory is quite full of rubbish...
Click to expand...

Not all that much rubbish.
 
K

krw

Just a side note for others who may be considering a larger supply.
For those of you building a box or just needing a supply keep in mind
the bigger the supply i.e., the higher the output wattage then
typically the more it costs to operate. If all you need is 350 watts
of output power (typically plenty for business apps.) and you purchase
a 1000+ watt supply then the added capacity is only generating heat
and costing you money to cool and operate.

Too many times people become wrapped around the axle sort of speak
with numbers rather than actual requirements. A general rule of thumb
for capacity is full load plus 125% for spikes and sustained
operation. The same number is used when fusing AC circuits.Some may
feel this is a bit conservative for general supply design but it
provides plenty of overhead.

Remember heat kills electronics. If you don't need the added
horsepower why heat your PC& house with an over sized supply.
<>< Rob
Click to expand...

Interesting. Yes, my room always get hot during the heat waves/summer
(up to 90F degrees) since I live in a desert area. I didn't know using a
more powerful PSU would cause more heat. I thought only when I use my
computers intensely (compiling, playing computer games [not Flash],
etc.) would cause this.

So based on my current primary computer setup
(http://zimage.com/~ant/antfarm/about/computers.txt ), I did not need
that SeaSonic 600 watts SeaSonic S12 PSU? If so, then how much powers
did I really need? Please note that I have tons of hardwares in my
primary PCs like four SATA drives, three TV tuner cards, an ATI Radeon
4870 HD video card, five fans, Intel Core 2 8200 CPU, etc. I will be
using most of the same hardwares for i7 setup. Will I still need that
much power?
Click to expand...

Plug the system into a Kill-A-Watt, PowerAngel, or some such, and find out how
much you're using. Multiply that by 1.3, 1.5, or whatever your "safety
margin" + PS (in)effiency factor, and there you go.
 
P

personaobscura

Even if both supplies are 90% efficient, the difference in heat output of a
1000W supply over a 350W supply is 185%. Even 65W is a lot of waste heat to
dissipate. The cost difference is trivial but it still is waste heat and more
importantly, at least to me, more noise.
Click to expand...

Wait. What?

Using your 90% efficiency for both examples, a 1000 watt supply driving a 350
watt load would be "wasting" only 35 watts. Guess how many watts a 350 watt
supply driving the exact same load would "waste".

Bonus question: Now guess which supply is likely to be generating more
electrical distortion on its outputs.

Double Bonus question: Guess which supply is likely to drive the owner to
distraction from its internal fan noise?
Not all that much rubbish.
Click to expand...

At least as much as your analysis ;-)
 
K

krw

Wait. What?

Using your 90% efficiency for both examples, a 1000 watt supply driving a 350
watt load would be "wasting" only 35 watts. Guess how many watts a 350 watt
supply driving the exact same load would "waste".

Bonus question: Now guess which supply is likely to be generating more
electrical distortion on its outputs.
Click to expand...

Electrical "distortion" on DC outputs? Properly designed, neither. IOW, not
enough information.
Double Bonus question: Guess which supply is likely to drive the owner to
distraction from its internal fan noise?
Click to expand...

I thought I mentioned that.
At least as much as your analysis ;-)
Click to expand...

Nope, not all that much.
 
R

Rev.3.20

Assuming you mean the Corsair AX750 that I gave a ref to,
it has low ripple (see the conclusion comments).

It is also a 80+ gold PSU, which means that at 10% usage
to 20% usage, which is where you'll be most of the time,
it is 82-to-88% efficient.

Also see:

http://en.wikipedia.org/wiki/Power_supply_unit_(computer)

and

http://en.wikipedia.org/wiki/80_PLUS

Bill
Click to expand...

OK, assuming efficiency and size has been established here's another
consideration concerning the earlier ripple mention.

Another side note that may be worth mentioning for Audio Video
applications is grounding. Provided you have a good ground your
usually OK but if not that's where your ripple factor will really be
noticeable. Older homes may not have ground receptacles (or have
ungrounded ground receptacles) which can allow AC hum and be very
apparent when working with audio. Typically cheaper designed power
supplies tend to have the noisiest outputs because of minimal
filtering. The fewer / least expensive components a manufacturer can
use the wider the profit margin is for them. A manufacturer can
produce a supply with what appears to be a great power output
specification but be the output voltages may not be very clean
resulting in AC Hum, easily heard in audio.

This is true of any audio design. Ever turn up an audio amp with no
input and listen to your speakers? The better designed filtering a
system has, the less hum you will hear. The same example can be heard
with TV audio. The noise is both audible and measurable. in any power
supply / amplifier circuit.

Granted most homes are grounded now days but older ones may not be.
One trick that can help this if running multiple PCs is to ground them
to each other.so that they have the same ground potential. Ideally
this isn't necessary but can help if needed.
 
D

DevilsPGD

In message <[email protected]> personaobscura
Using your 90% efficiency for both examples, a 1000 watt supply driving a 350
watt load would be "wasting" only 35 watts. Guess how many watts a 350 watt
supply driving the exact same load would "waste".
Click to expand...

Keep in mind that a PSU designed to be 90% efficient delivering 1000w
will likely not be 90% efficient delivering 350watts.

It certainly won't be wasting 10% of it's maximum capacity at all times,
but most PSUs aren't as efficient when running outside their designed
output ranges.

http://www.overclock3d.net/reviews/power_supply/corsair_hx650w_650w_atx_psu/4
is one such example, where efficiency ranges from 75%-88% dependant on
load.
 
Y

Yousuf Khan

True.<crap> ...except that a 1kW power supply may be a lot less efficient
at 1/3 of its rating.
Click to expand...

The 80-Plus rating is a type of guarantee of 80%+ efficiency at several
load levels, from 20% on upto 100%. There will be a level at which any
power supply will be most efficient somewhere between that (perhaps
it'll be 90% efficient at that level), but it should remain at or above
80% efficiency all throughout its range.

Yousuf Khan
 
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