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  Topic Review (Newest First)
06-14-2016 02:24 AM
jrlaudio Hi all,

What I think causes many problems here is in computer land people talk about "watts" and even benchmark in "watts". However, when talking about PSU's in general, the considerations should be voltage and current. The reason is you could have in one situation low voltage and higher current, and in another high voltage and lower current; however in both the power (watts) measurement could be identical. So using watts as the sole criteria is not really indicative of the need or problem.

A "Watt" is power; a rate of energy calculation of voltage and current. Specifically a watt (W) is when one ampere (A) of current flows through an electrical potential difference of one volt (V).

1 W = 1V ⋅ A

So this means, if you have a 1 volt rail and a current draw of 1 amp the rate of energy or power is 1 watt. Also if you have 100 volts and a current draw of .01 amps you still have 1 watt. Also if you have .5 volts and 2 amps of current draw it is still only 1 watt. So to be using 1 watt of power on a 12 volt rail, you need to draw approximately .08 amps.

So you can see that power measurements can be useless in any application using a PSU. Even using power to determine what PSU to use in a given application is not wise. It only indicates the rate of total energy; it does not tell you anything more than that rate. What is relevant is knowing the amount of current drawn or required on each voltage rail.

When choosing a PSU for any electrical use, the primary factor is the amount of current that will be drawn from any voltage rail. Once you exceed (or reach a practical limit) of current draw on a given voltage rail, this is when you see voltage drop across that rail. (What I see some computer enthusiasts incorrectly refer to as "V-droop"). So what is important to understand is you must calculate the max current need for each voltage rail and choose a PSU that will deliver more than that amount current, since headroom on current (sometimes refereed to as "duty cycle") prevents issues like voltage drop and excessive heating.

Talking about power alone is pointless.

As far as the issue of running multiple power supplies (other than for redundancy applications), the issues and problems are due to the nature of how a PSU functions; how it converts wall AC voltage to usable DC voltages and current for a computer to use. Without getting too technical in how this is accomplished, most PSU designs require that the two PSU's be "linked" in some fashion. In most cases in this link, the grounds are bridged common and sections of the circuitry involved in regulation (like timing) are synced.

One of the few manufacturers making computer PSU's that offers this form of linking is Antec in the "High Current Pro" series. This is what Antec calls "OC Link". By connecting two PSU's of this series together, you can increase the total current available, and use all the connections on both PSU's in the same computer without any worry of problems. I am sure their are other manufacturers who offer this type of linking, however this series by Antec is the one I know of at this writing.

When using two PSU's in the same build it is important to understand that it is not sufficient (or safe) to simply connect two PSU's together or even to use some third-party "external device" alleging it can safely connect PSU's together externally. The linking of two PSU's must be internal, built-in as a feature and is proprietary to each design type of PSU.
06-05-2015 04:27 AM
klepp0906
Quote:
Originally Posted by warpuck View Post

I read this entire Thread.
It is kinda old, but for those who read it in the future.
One of the the things I have done is High power RF systems (megawatts). In those systems you will not find dual power supplies feeding the same component. Some power supply may be grounded to the case. So what happens if you do? supply a and supply b say puts out 12.012 V and b 12.125 volts. where does . 0.112 volts go ? answer into supply a. consider that supply as a low ohm (resistance) say .001 ohm. 0.112 v divided by .01 ohm = 110 amps. When that happens power supply a and b become a temporary smoke generators and the best designed one survives. So any thing plugged in to the mother boards (video cards) must be powered from the same source. These devices draw power through the Motherboard.
Hard drives, CD drives, fans, & pumps can be powered by a separate supply because they are only signal connected and not electrically connected. The only that things may require enough current draw to warrant a separate power supply are TEC, some pumps and a few high volume fans or enough fans to make the box fly.
I have found that the silver or gold power single rail supplies last longer. If 1300 watts can't power it you probably should not build it. For those of us who have to live off 110 volts, 1300 watts is getting close to popping the circuit breaker on a 14 gauge circuit.


QFT. I use dual evga classified psus on my rig because 1 would trip every time I run any type of benchmark (shut down around 1650 watts) and I added the second which solved that problem but began tripping my circuit breaker instead. At that point i had to use each psu on a seperate circuit. Not ideal but atleast it runs without trouble until I can get a few 220 lines into my office lol. Eager to see the look on the electricians face tongue.gif

I use one solely for the 4 Titans which with a custom bios use a dramatic amount of power themselves.

I agree in most scenarios 2 psus will never be necessary but in some of today's high end custom builds it certainly isn't overkill. I measured 2200w at the wall without having waterblocks on my titans at that point. Gives my 24k btu AC a run for its money lol.

Just had a baby and doing tons of Reno around the house and so I havnt had the pc hooked up for the last month and it cut our electric bill very close to 50% ugh! The price we pay to jam video games!
09-23-2014 11:03 AM
warpuck I read this entire Thread.
It is kinda old, but for those who read it in the future.
One of the the things I have done is High power RF systems (megawatts). In those systems you will not find dual power supplies feeding the same component. Some power supply may be grounded to the case. So what happens if you do? supply a and supply b say puts out 12.012 V and b 12.125 volts. where does . 0.112 volts go ? answer into supply a. consider that supply as a low ohm (resistance) say .001 ohm. 0.112 v divided by .01 ohm = 110 amps. When that happens power supply a and b become a temporary smoke generators and the best designed one survives. So any thing plugged in to the mother boards (video cards) must be powered from the same source. These devices draw power through the Motherboard.
Hard drives, CD drives, fans, & pumps can be powered by a separate supply because they are only signal connected and not electrically connected. The only that things may require enough current draw to warrant a separate power supply are TEC, some pumps and a few high volume fans or enough fans to make the box fly.
I have found that the silver or gold power single rail supplies last longer. If 1300 watts can't power it you probably should not build it. For those of us who have to live off 110 volts, 1300 watts is getting close to popping the circuit breaker on a 14 gauge circuit.
09-04-2013 11:55 AM
freeleacher If you don't have enough amps on your 12v rail its the best thing to do,
In fact it will be better because your not stressing the power supply.
Allso its much cheaper to do it this way and get better thermal results.
12-07-2012 03:53 AM
Gadgety
Quote:
Originally Posted by Phaedrus2129 View Post

The short answer: Don't.
The vast majority of people who use two power supplies don't need to, and waste money or endanger their rigs doing so. It's only a valid approach in a very small handful of scenarios, and is otherwise either an unnecessary over-complication, or a dangerous jury rig solution.
The main thing people do wrong with dual power supplies is to think they even need it. They look at a GTX580, then look at power consumption charts and think "OMG 500W OMG OMG NEED MOAR POWER" when in fact that's the total system power consumption; the card itself only pulls ~300W. So then they decide to supplement their already more-than-sufficient 650-850W PSU with another PSU, wasting money and making life more difficult, what with having to stash another PSU somewhere inside their case and hiding a bunch more cables.
The next worse thing people do is do dual PSUs with cheap units. Most power supplies under $100, and all under $50, use a technology called "group regulation" to reduce costs. There's a bunch of technical stuff I could throw at you; but the gist of it is that the current on the +12V and +5V rails on a group regulated power supply must stay within a certain approximate ratio to one another (say 3A of +12V for every 1A of +5V, +/-20%) or else the voltage regulation will go out of whack. +12V load too low? +5V voltage drops and +12V voltage soars. +5V load too low? +5V soars and +12V drops.
The secondary PSU in a dual-PSU usually has no +5V load at all, or at most 1-2A, meaning that the +12V voltage will droop significantly; on high-end group regulated units it will fall to 11.6-11.7V, which is in-spec but poor. On low-end group regulated units +12V might drop to 11.3-11.5V, out of spec or almost. Out of spec voltage (>11.4V) can cause component malfunction; bluescreens and random shut downs, and will prevent many hard drives from functioning at all.. Very low, but in-spec voltage (11.4-11.6V) can cause poor overclocking results, occasional instability, excessive wear on component power circuitry, and can cause hard drive issues over time.
Dual PSUs should only be used when both power supplies are high quality and use independent regulation, or even better "DC-DC" regulation. It's only a useful approach when dealing with systems that pull >1000W; then two quality 650W+ indy/DC-DC regulated units may be used in place of a single 1000W+ unit. Even then you may run into issues of crosstalk leading to greater effective ripple on power regulated devices (motherboard, graphics card, RAID controllers), and units that rely on +12V v-sense may suffer poor voltage regulation if the cable with their v-sense wires is not in use.
So just don't.

I would prefer one power supply but may have to go with two. Two Xeon5650 oc to 4.0GHz, 3xGTX580s + 1 Quadro, water cooled. This is a work station, and I won't be using headsets, or listen to gaming sound effects, so noise control is important. I get 1675W with 30% aging on the extreme psu calculator. I'm locating the radiator and fans in the basement below my home office and looking for the least noisy PSU solution that can handle the wattage. The case I'm using has max 30+6 cm extended space for the power supply (-ies). I looked into 2x Corsair AX860i's which will be 32 cm without the cabling.

Any suggestions?
05-30-2012 09:24 PM
simurg
Quote:
Originally Posted by Levesque View Post

Like I care what you think... And 2 weeks later, you had to put your little grain of salt with a comment about me, adding nothing to the discussion about dual-PSU... Wow. It was so worth it. I'm happy you took the time to wrote that. rolleyes.gif
A little come back to me dual-PSU adventure.
Everything is now working fine with my Antec HCP-1200 powering 4X 6970 Lightning + 3930k + Rampage IV + all HDDs and SSDs, and my AX850 is powering all the fans and watercooling pumps 4X MCP655. Dual-PSUs working perfectly nowwith the Lian-LI dual-PSU adaptor. So I really think it was the Add2PSU adapter the culprit..
The HCP-1200 is noisy, but it's rock-stable with 4X 6970 at 1050/1475 1.3v. smile.gif

I also have one of those similar adapters. My problem is that the second Power Supply does not stop after first one is stopped. Do you have the same experience?
12-19-2011 04:03 AM
Ken1649
Quote:
Originally Posted by sockpirate View Post

Quote:
Originally Posted by Ken1649 View Post



LOL

Look at it this way, some people will link you of what they "read" and convince you what they believe from what they read.

I have seen they link a unit rated continuous 1,200w is capable of 1,700w in the review. But it's not scpecified the continuous draw of 1,700w lasted how long for the test period. So they are saying your Quad setup max power draw is 1,300w hence that unit is what you need.

Most monufactures state the MTBF is 100,000 hours = 11.41 years. Best manufactures warranty have seen so far is 7 years. Why?



 
 

So help me out here? My single AX 1200 is enough then is what you are saying ? Sorry i am a bit dense, and it is also 330AM frown.gif


Here, have a look of real world user experience. The fact is fact regardless of personal opinions and whatever reviews people read and suggested to you.

 

https://www.overclock.net/t/1186014/how-to-distribute-load-on-enermax-maxrevo-1500w#post_15974914

 

12-18-2011 07:29 AM
Ken1649
Originally Posted by Levesque View Post


Like I care what you think... And 2 weeks later, you had to put your little grain of salt with a comment about me, adding nothing to the discussion about dual-PSU... Wow. It was so worth it. I'm happy you took the time to wrote that. rolleyes.gif

A little come back to me dual-PSU adventure.

Everything is now working fine with my Antec HCP-1200 powering 4X 6970 Lightning + 3930k + Rampage IV + all HDDs and SSDs, and my AX850 is powering all the fans and watercooling pumps 4X MCP655. Dual-PSUs working perfectly nowwith the Lian-LI dual-PSU adaptor. So I really think it was the Add2PSU adapter the culprit..

The HCP-1200 is noisy, but it's rock-stable with 4X 6970 at 1050/1475 1.3v. smile.gif


Try run 3DMark 11 with a single PSU then compare the scores with distibuted loads among 2 PSUs thumb.gif

 

Difficult to explain if not to test it yourself. Reviews don't always covered everything other to say how good that specifics unit in review tongue.gif

 

12-16-2011 09:05 AM
sockpirate
Quote:
Originally Posted by jellis142 View Post

Ok, with Surround there will be more load, but all of them still won't get to 100% load, scaling isn't that perfect yet tongue.gif

He he yeah i figured. I dunno i just really wanna figure out what to do...i came here because my thread i started turned into nonsense and i was directed here by a friend. I am still at a loss of what to do... mad.gif cannot get a straight answer as what i will be fine with doing , without endangering my parts in the process when everything is overclocked on 3x 120 hz monitors.
12-16-2011 08:50 AM
trumpet-205
Quote:
Originally Posted by Phaedrus2129 View Post

Antec HCP-1200, Corsair AX1200, Thermaltake Toughpower 1350M, Silverstone ST-1500, Enermax Platimax 1200W

Didn't you say that AX1200 is a single rail design?
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