hot deals on a PSU

[dxpaap]

If you go to the AMD web site and look at the "Builders Guide for desktop/ tower systems" it shows the AMD Athlon gets it power off the 12 v rail (eg - XP1800 1.533 GHz, 1.75V uses 6.87A or 82.44 watts). Not sure if this is true for all CPU's. This table shows by component typical Amps used and which rail - very helpful (unfortunately, I printed this guide out but didn't save the URL - think I got it from an Anandtech thread)

Also, it had a nice write up on air flow - shows that a two fan PSU has significant improvement on cpu cooling (draw from the bottome of the PSU - when installed next to the case exhast fan greatly improve air flow across the cpu HSF - as opposted to a PSU that has one fan and draws air from the back of the PSU).

my two cents worth

 

[BentValve]

Originally posted by: render

The CPU does not use the 3.3 and 5v lines AT ALL!!!!

Wrong. Most Athlon MBs use 3.3 and 5v for CPU. Intel started to use 12V for their cpu with 4-pin 12V connector.

And you got this info from ???????????

 

[mindless1]

Originally posted by: BentValve
The CPU does not use the 3.3 and 5v lines AT ALL!!!! It uses the 12V rail buddy.

Did you read my earlier posts? If the motherboard has the ATX12V 4-pin connector, it's using 12V to supply the power for the CPU. Most Athlon motherboards don't use 12V for CPU, nor do most Durons or any Tualatins, Coppermines, C3, K6, etc, etc, etc... see the trend here? I'm surprised that anyone would doubt this, it's been common knowledge for quite a while. Where do i get this info? I don't need to get this info from anyone, I have the ability to find out with real-world testing in addition to the gazillion hits a Google search would turn up.

 

[Bonesdad]

If you look waaay back on this post, I said the same thing, that I was suspicious of the original post by HumblePie, and that this article from Firingsquad.com and this article from Tom's Hardware Guide BOTH said that CPUs (AMD included) run off the 12v rail. Didnt trust the opinions I was getting here (no offense, bear with me). So I wrote to the author of the Firingsquad.com article about PSUs. Well, below is his response to my email...


FiringSquad always tries to balance our articles with the appropriate level
of detail. Make things too simplistic and the article is useless. Make
things too complex, and many readers will get lost in the details. In the
case of the power supply article, we probably were a bit too simplistic.

Many Athlon boards derive the CPU core from the +5V. Modern Athlon boards
including the nForce2 use the +12V. In fact, if you look at AMD's own
technical documents (where we received our values) they indicate that the
CPU should run off the 12V rail.

http://www.amd.com/us-en/Processors/ProductInformation/0,,30_118_756_3734^37
48,00.html

The issue is that it's cheaper and more efficient to run on the +5V core.
Unsurprisingly, many motherboard manufacturers choose to do this. Moving to
the +12V rail is something you'll see happening more often, however, because
it provides additional stability, particularly when it is under load. You
can not easily tell which rail the CPU core voltage is derived from just by
looking at the motherboard.

Choosing a power supply is a complex task, however, in our experience, the
limiting factor is the +12V rail. The true measure of the power supply is
difficult since one must determine the power budget from one's system -- as
I mentioned earlier, motherboards vary on whether they draw from +5V or +12V
(though both AMD and Intel specs call for +12V), and system peripherals also
vary. In addition, many power supplies with excellent +3/5V combined power
are insufficient for a similar system whose motherboard relies on the +12V
rail. Add the fact that power output can vary by operating temperature, and
that power supply ratings can be questionable, and it becomes a more complex
question.

We believe that if you chose your power supply based upon the assumption
that the CPU runs on the +12V rail, you will end up choosing a power supply
capable of supporting your system, regardless of whether the motherboard
actually draws from the +5V or +12V rail. On the other hand, if you chose a
power supply with sufficient +5V power, you may find yourself out of luck
with a AMD motherboard that derives the CPU voltage on the +12V rail. That
is, power supplies that can handle large CPU current on the +12V rail almost
certainly have adequate +3/5V power.

Sincerely,
Alan Dang


So....it seems that whether or not your AMD CPU uses the 12v or 5v rail is in part dependent on your mobo. It seems its far too simplistic to say "CPUs run on the 5v rail" or "CPUs run on the 12v rail". You gotta do your homework boys & girls!!! I tend to agree with Alan Dang...choose the PSU based on the 12v rail and you will probably do alright... responses????

 

[dxpaap]

so does anyone know what rail an AMD 1600+ would use on an ECS K7S5A mob ?

thanks

PS - thks for the informative discussion - I'll get this straight with a little help yet !!

 

[mindless1]

ECS K7S5A uses 5V for CPU.

Best deal on a PSU for that would be the LiteOn on sale at Directron.

 

[BentValve]

Interesting, lets use this AMD high performance system as an example....HERE

Lets move the CPU usage to the 5V rail instead of the 12V rail, currently it uses 7.5 amps of the 12V rail.....we move it and now its using 18amps, look at the fact that now we have about a 35amp draw (max load) on the 5V rail, umm you had better have a sweet PS to handle this! Total load on the 3.3 and 5v lines can now reach a whopping 200watts!
Meanwhile the 12V line which is the beefiest of them all on pretty much every power supply now has nothing to do.

 

[docinthebox]

According to Alan Dang:

The issue is that it's cheaper and more efficient to run on the +5V core.
Unsurprisingly, many motherboard manufacturers choose to do this. Moving to
the +12V rail is something you'll see happening more often, however, because
it provides additional stability, particularly when it is under load. You
can not easily tell which rail the CPU core voltage is derived from just by
looking at the motherboard.

Does that mean maybe higher-end motherboards use the +12V rail for the CPU while lower-end ones use the +5V rail? (since it's cheaper for the mobo manufacturer to run the CPU on +5V, at the expense of stability.)

 

[mindless1]

Originally posted by: docinthebox
Does that mean maybe higher-end motherboards use the +12V rail for the CPU while lower-end ones use the +5V rail? (since it's cheaper for the mobo manufacturer to run the CPU on +5V, at the expense of stability.)

What do you consider high-end? I would take that email with a LARGE grain of salt... consider a certain well respected manufacturer (Asus) a certain nForce2 motherboard (A7N8X) CPU power circuit using 5V

 

[docinthebox]

Originally posted by: mindless1
What do you consider high-end? I would take that email with a LARGE grain of salt... consider a certain well respected manufacturer (Asus) a certain nForce2 motherboard (A7N8X) CPU power circuit using 5V

I think the A7N8X in fact uses the +12V rail to power the CPU. From p.1-13 of the A7N8X manual:

"3. ATX power connectors (20-pin ATXPWR1)

These connectors connect to an ATX 12V power supply... <snip>

If you will need to replace the power supply in the future, make sure that your new ATX 12V power supply can provide 8A on the +12V lead and at least 1A on the +5-volt standby lead (+5VSB). The minimum recommended wattage is 230W, or 300W for a fully configured system. The system may become unstable and may experience difficulty powering up if the power supply is inadequate." (I'm tired... so much typing.)

Could you give some explanation as to why you think the A7N8X uses the 5V for CPU power based on the image you quoted from Firingsquad?

 

[BentValve]

Could you give some explanation as to why you think the A7N8X uses the 5V for CPU power based on the image you quoted from Firingsquad?

Ditto , lets hear it.

 

[mindless1]

Originally posted by: docinthebox
I think the A7N8X in fact uses the +12V rail to power the CPU. From p.1-13 of the A7N8X manual:

"3. ATX power connectors (20-pin ATXPWR1)

These connectors connect to an ATX 12V power supply... <snip>

If you will need to replace the power supply in the future, make sure that your new ATX 12V power supply can provide 8A on the +12V lead and at least 1A on the +5-volt standby lead (+5VSB). The minimum recommended wattage is 230W, or 300W for a fully configured system. The system may become unstable and may experience difficulty powering up if the power supply is inadequate." (I'm tired... so much typing.)

Could you give some explanation as to why you think the A7N8X uses the 5V for CPU power based on the image you quoted from Firingsquad?

If the system used 12V for the CPU the recommended Amperage for 12V rail would be higher, a PSU with 8A 12V rail is a VERY low-end, old or mATX PSU. If the mosfets received 12V in they would need the 4-pin plug nearby feeding the caps on the high-side on the regulators (right side of linked pic). BTW, that's not just the normal verison of the A7N8X, that's the Deluxe, a top-of-the-line motherboard. I suspect that this is a generic notation in the Asus manual, you don't really expect them to keep drawing and typing the same sections over and over again for each new motherboard, do you?

 

[mechBgon]

I think Sparkle Power/Fortron Source units are very good, and recommend them frequently for their value + quality, but I think you might be getting carried away throwing the "1% regulation" thing around. Check here and then check here, those are the actual specs for the FSP350-60BN and the TruePower330. As you can see, the specs for the Antec are as tight or tighter on every line in the Load Regulation (ie, when the computer has a mood swing and powers a bunch of stuff up at once).

The equivalent 350W PC Power & Cooling also has looser Load Regulation (±5%), as you can see here. That doesn't mean it's bad, of course, because last I knew, the PC P&C units were built by Zippy, a little-known company that builds very high-quality units like Delta does and is more into the server market.

Incidentally, since I haven't seen it mentioned yet, the TruePowers don't give a "combined" 3.3V + 5V rating on the label. Why not...? Because the two lines are fully independent, unlike the majority of consumer-level PSUs which draw those two voltage lines from a common source (hence the significance of the "combined" rating). The actual combined 3.3 + 5 on a TruePower 330 is 242W if you do the W=V x A math... very nice, almost as high as Antec's previous 400W unit (245W). The TP430 has a whopping 272W. I'm somewhat of an Antec fan simply because they back up their (3-year) warranty the way you'd want, and I now have over 20 Antec case/PSU's at work as a result.

 

[docinthebox]

Originally posted by: mindless1
If the mosfets received 12V in they would need the 4-pin plug nearby feeding the caps on the high-side on the regulators (right side of linked pic).

Why can't the 20-pin connector feed the capacitors you mentioned?

(Just trying to understand the reasoning behind.)

 

[BentValve]

Originally posted by: mindless1
ECS K7S5A uses 5V for CPU.

Best deal on a PSU for that would be the LiteOn on sale at Directron.

Have you ran any tests on this power supply?

 

[mindless1]

Originally posted by: docinthebox

Originally posted by: mindless1
If the mosfets received 12V in they would need the 4-pin plug nearby feeding the caps on the high-side on the regulators (right side of linked pic).

Why can't the 20-pin connector feed the capacitors you mentioned?

(Just trying to understand the reasoning behind.)

Look at any other motherboard that DOES use the 12V for CPU (for example, here is an Asus that does. Asus, like all other manufacturers, has an option... they can either power the CPU by 5V utilizing the 5V power plane, or they need to GET the power there somehow. No manufacturer relies on a single 12V lead from the PSU, to a single point on the ATX connector, to a single trace on a motherboard, to move ALL the power to the CPU across the entire motherboard. It just isn't done, period. No motherboard is designed THAT badly. The whole reason intel developed the ATX12V PSU in the first place was to have a connector for when the CPU DOES use 12V. Again I say that anyone can choose to disbelieve, i have no reason to make this claim unless I'm involved in some conspiracy against ATX12V PSU or Firing Squad

 

[mindless1]

Originally posted by: BentValve

Originally posted by: mindless1
ECS K7S5A uses 5V for CPU.

Best deal on a PSU for that would be the LiteOn on sale at Directron.

Have you ran any tests on this power supply?

Not what I'd call extensive testing because I don't have that equipment here, these LiteOns are for a system I was building, and as spares. One is powering a system right now (the first one I bought from the last Directron deal).

The rails stay constant regardless of load (checked with meter), it has oversized componentry, high quality fan, superior MTBF rating, and it qualified for servers by Compaq which says enough by itself. I haven't hooked it up to a scope but I don't feel that I need to. LiteOn doesn't have the spec sheet for that particular model, but does offer specs for several similar models on their website.

 

[docinthebox]

Originally posted by: mindless1
Look at any other motherboard that DOES use the 12V for CPU (for example, here is an Asus that does. Asus, like all other manufacturers, has an option... they can either power the CPU by 5V utilizing the 5V power plane, or they need to GET the power there somehow. No manufacturer relies on a single 12V lead from the PSU, to a single point on the ATX connector, to a single trace on a motherboard, to move ALL the power to the CPU across the entire motherboard. It just isn't done, period. No motherboard is designed THAT badly. The whole reason intel developed the ATX12V PSU in the first place was to have a connector for when the CPU DOES use 12V. Again I say that anyone can choose to disbelieve, i have no reason to make this claim unless I'm involved in some conspiracy against ATX12V PSU or Firing Squad

Good explanation. Thanks!

 

[ivwshane]

So if mobos are drawing from the 12v rail then what number or info do we need to be concerned with when looking at power suplies?
If one had a beefy system and a mobo that drew it's power from the 12v rail would the fortron 350w still be a good choice? If so why? if not, why not?







This thread should be moved to a more permanent and better home

 

[RLE]

Meanwhile the 12V line which is the beefiest of them all on pretty much every power supply now has nothing to do.

Well, except of course power all your various drives. A typical IDE drive will suck up 2A on spin-up. Stick 4 or 5 drives in a box and the 12V rail will be plenty busy when you boot your box.

 

[rootaxs]

Forgive me for jumping in on this again, but after reading all the previous threads past page 1 it seems everyone has been arguing more on specs than real life performance on power supply units.

I, for one, have the Forton. And for anyone who read my previous posts will know what load it's under. Granted it's not a completely top-of-the-line system, but it holds it's own - stable - OC'd or otherwise.

 

[BentValve]

Originally posted by: ivwshane
So if mobos are drawing from the 12v rail then what number or info do we need to be concerned with when looking at power suplies?
If one had a beefy system and a mobo that drew it's power from the 12v rail would the fortron 350w still be a good choice? If so why? if not, why not?

Since all power supplys are not created equal and the specs written on them are not always accurate then this seems logical to me:
Choose a power supply by the pound




The Compaq server PS that Mindless1 listed looks like a very good one, its weighs like 5lbs, my Antec 350 watt PS only weighs 3.5lbs... @18.99 each you can bet I snatched one of them up.
I am going to put a few dummy loads on it and give it a workout, if it stands up to my tests then I am gonna buy a few more of them.

EDIT: link to the Compaq server PS: HERE

 

[Zepper]

I recently ordered the 250W Sparkle from Newegg and I'm very happy with it. It has a fan speed regulator built in and is normally very quiet. It's also a fair bit heavier than the 250W Enlight it replaced. I'm using it on my old K6-2/500 system. As others have pointed out, Sparkle is another label for Fortron/Source Group. The original Fortron/Source distributor in the States was, shall we say, incompetent in custormer relations and other areas so the name got a bad rep in the distribution channels, thus the new name(s).
. Another highly rated PSU in Tom's Hardware comparison was Herolchi [sic] (actually Heroichi) which is apparently distributed here by Compucase and sold on Newegg under that heading. It looks like Newegg has dropped the prices on them so they are now competitive w/ Sparkle. In their favor, they are actually in stock. Whereas many of the Sparkle models aren't.
.bh.


sleefer et al.,
. Actually, Active (PFC) Power Factor Control, doesn't reduce power usage, it just makes the PSU look to the power line like a resistive load instead of a reactive one. This makes for a reduction in the meter reading and thus a lower power cost, but the power used is really still the same. This is to compensate for a foible in power meters, not to make your PSU "greener". If you want a green PSU, turn it off when not in use! It's really only useful where a bunch of PCs are in use for many hours a day. .bh.

 

[mindless1]

Originally posted by: BentValve

Originally posted by: ivwshane
So if mobos are drawing from the 12v rail then what number or info do we need to be concerned with when looking at power suplies?
If one had a beefy system and a mobo that drew it's power from the 12v rail would the fortron 350w still be a good choice? If so why? if not, why not?

Since all power supplys are not created equal and the specs written on them are not always accurate then this seems logical to me:
Choose a power supply by the pound
The Compaq server PS that Mindless1 listed looks like a very good one, its weighs like 5lbs, my Antec 350 watt PS only weighs 3.5lbs... @18.99 each you can bet I snatched one of them up.
I am going to put a few dummy loads on it and give it a workout, if it stands up to my tests then I am gonna buy a few more of them.

EDIT: link to the Compaq server PS: HERE

One thing I want to make clear about that linked LiteOn PSU... it's not ATX12V, no 12V 4-pin connector. Although it is a good PSU, if I were powering a P4 or Athlon system using 12V for CPU I would recommend the Fortron 350W over this PSU with an adapter. More description of the LiteOn PSU is available in this thread.

 

[BentValve]

Originally posted by: mindless1

Originally posted by: BentValve

Originally posted by: ivwshane
So if mobos are drawing from the 12v rail then what number or info do we need to be concerned with when looking at power suplies?
If one had a beefy system and a mobo that drew it's power from the 12v rail would the fortron 350w still be a good choice? If so why? if not, why not?

Since all power supplys are not created equal and the specs written on them are not always accurate then this seems logical to me:
Choose a power supply by the pound
The Compaq server PS that Mindless1 listed looks like a very good one, its weighs like 5lbs, my Antec 350 watt PS only weighs 3.5lbs... @18.99 each you can bet I snatched one of them up.
I am going to put a few dummy loads on it and give it a workout, if it stands up to my tests then I am gonna buy a few more of them.

EDIT: link to the Compaq server PS: HERE

One thing I want to make clear about that linked LiteOn PSU... it's not ATX12V, no 12V 4-pin connector. Although it is a good PSU, if I were powering a P4 or Athlon system using 12V for CPU I would recommend the Fortron 350W over this PSU with an adapter. More description of the LiteOn PSU is available in this thread.

I realize that it will not work for a P4 system however I have been researching the AMD 12V thing, so far I have yet to find a single slot A motherboard that uses the 12V rail to power the CPU, yet AMD uses the 12V rail as their example in their system builders guide,
HERE

I just got off the phone with AMD and was told that they are pushing mobo makers to use the 12V rail to power the PS due to its advantages in higher frequencies and stability yet he had no information on any particular motherboard.
He told me that each mobo maker can supply the CPU however they want .



So it seems that lite on is quite an adequate power supply for most AMD XP based systems, especially those that only use one or two hard drives. There is even enough power on the 5 and 3.3 v rails to overclock the ram and CPU as much as you could possibly want.