Help!! A fubar psu

[Jaco]

D_A, noone's right or wrong here imo .
Newer PSU's have more power available on the 12v rail.
This one here has a lot of power on the 3,3v & 5v rail which tells me it's an old design PSU. That 260GTX pushed it over the edge imo.
My Pc Power & Cooling 370w for instance has 27A available on the 12V rail. (and 82% efficient, while this one is ~70%)

[STEvil]

What Jaco said.

Old PSU's had to power the CPU from the +5v rail a lot of the time so they could have upwards of 50A available on it. These days most of the system uses +12v for power.

On a mainstream system the PSU would probably have been fine. They are not loaded to 100% 24/7 and do not have big power hungry GPU's :p

[D_A]

My contention boils down to this: the rated output of a PSU includes more than just the 12V rails. It is the full load power that can be delivered across ALL supply rails simultaneously. The affirmation I am arguing against was that the PSU was not a 430W unit as listed but of a lower wattage because the 12V rails did not supply close to the full rated power and that the power supplied to the 3.3 and 5V rails did not count toward to unit rating.
As yet nobody has provided anything even resembling a counter point to my contention which holds consistently for PSUs of any vintage, again something that has not been contradicted in any way.

Does anybody want to try and prove how almost 200 Watts of supply capacity doesn't count toward the output of a PSU? So far I've seen a lot of side-stepping and dodging and now trying to pull the "no-one is right or wrong" routine, but not one counter point or element of proof aside from that which holds up my case.

[Sparky]

I don't even get what the heck the argument is about, or why there is one?

[Tom128]

As others have said, if it was a good PSU you can probably use the other parts still. If it was a piece of crap you might be taking a risk even trying to test the other parts though. I learned my lesson a few years ago with a $19.99 PSU from microcenter. Two of the wires on a molex fused together (assume weak/missing insulation on part of one wire) and fried most of the system, including a brand new at the time 8800GT. I don't know if it was related or not, but in my testing to see if the 8800GT still worked, I put the card into another motherboard and that board, which had worked without issue for years, stopped working. I assumed the video card had something fused as well and shorted out the other board.

Lesson learned - if there is one part in your build you should spend money on, it's the PSU.

[[XC] Oj101]

My contention boils down to this: the rated output of a PSU includes more than just the 12V rails. It is the full load power that can be delivered across ALL supply rails simultaneously. The affirmation I am arguing against was that the PSU was not a 430W unit as listed but of a lower wattage because the 12V rails did not supply close to the full rated power and that the power supplied to the 3.3 and 5V rails did not count toward to unit rating.
As yet nobody has provided anything even resembling a counter point to my contention which holds consistently for PSUs of any vintage, again something that has not been contradicted in any way.

Does anybody want to try and prove how almost 200 Watts of supply capacity doesn't count toward the output of a PSU? So far I've seen a lot of side-stepping and dodging and now trying to pull the "no-one is right or wrong" routine, but not one counter point or element of proof aside from that which holds up my case.

The thing is, if you buy a 1KW PSU which has 950w available on the 3.3v and 5v rails and only 50w on the 12v rail, you'd call that misleading, right? A 1KW PSU that can't power an absolutely entry level system? Sure, you wouldn't buy a PSU like that, but what about Joe Average? 1KW, hmmm, should last me a long time. Unless you have more hard drives than fingers, the lower voltage rails mean very little. In general, a good modern PSU will have almost all of its power available on the 12v rail

[Otis11]

Lesson learned - if there is one part in your build you should spend money on, it's the PSU.

QFT

[D_A]

The thing is, if you buy a 1KW PSU which has 950w available on the 3.3v and 5v rails and only 50w on the 12v rail, you'd call that misleading, right? A 1KW PSU that can't power an absolutely entry level system? Sure, you wouldn't buy a PSU like that, but what about Joe Average? 1KW, hmmm, should last me a long time. Unless you have more hard drives than fingers, the lower voltage rails mean very little. In general, a good modern PSU will have almost all of its power available on the 12v rail

Go back and read my post on how they are built for purpose. You've missed my point there entirely.

I don't know what technically illiterate reviewer sprouted that phase about a "good modern PSU" but it's twaddle! A "good modern PSU" has high efficiency, excellent voltage regulation and is built to "fail safe", meaning it will not damage other components when it dies. A LARGE OUTPUT modern PSU will have most of it's output on the 12V rails because that's what they're built for, to power multiple additional devices. A MODERATE TO SMALL OUTPUT modern PSU will NOT necessarily have most of it's output on the 12V rails because the 3.3 and 5V lines take up a proportionally greater amount of the PSU's output. Remember your motherboard alone without the PSU can still be pulling 80W. Don't believe me? Where do you think the energy comes from the make all those ICs hot? It ain't Red Bull sunshine, it's the PSU!

[[XC] Oj101]

But what happens when Joe Average sees that he needs a 450w PSU for his new Radeon 6990 and thinks to himself, "Hmmm, I'm set" not realising that with his low end PSU he has under 200w available on the 12v rail? PSUs SHOULD, and this is purely my opinion so feel free to disagree, be rated ONLY by their 12v rail and come with a strong enough 3.3v and 5v rail as a given. Strong enough to power at least a dozen hard drives.

I'm not fighting with you, merely having a good debate

[STEvil]

But what happens when Joe Average sees that he needs a 450w PSU for his new Radeon 6990 and thinks to himself, "Hmmm, I'm set" not realising that with his low end PSU he has under 200w available on the 12v rail? PSUs SHOULD, and this is purely my opinion so feel free to disagree, be rated ONLY by their 12v rail and come with a strong enough 3.3v and 5v rail as a given. Strong enough to power at least a dozen hard drives.

I'm not fighting with you, merely having a good debate

PSU's do usually list the combined 12v rating. In smaller print :/

[D_A]

STEvil has a good point. That information is available.

It's worth noting the Joe Average doesn't normally mess around inside their system case. When he DOES that's when hardware techs get to open his case, look at the mess, give the fool a contemptuous glare and proceed to add up the cost of many replacement parts. Protests of "I know what I'm doing!" usually resulting in extra percentages being added to the repair cost as a PMO factor (that's Pissed Me Off in case you were wondering).

As for what SHOULD be there, well there is some merit to that suggestion. In the case of a 1KW or larger PSU it really is all about having buckets of 12V supply for those GTX580 in triple SLi, the 200W peltier blocks, triple 140mm fan radiator, dual coolant pumps, 8TB RAID array, enough neons to light up Vegas, 16GB omgwtf GHz RAM and quad 4.6GHz HTT Ten core CPUs. On that rig the 3.3 and 5V rails, as vitally important as they are, comprise only a small proportion of the total system power. People don't generally think about it but different motherboards can have very different power consumption. I don't recall seeing the 3.3v and 5V requirements of motherboards on the packaging (not saying it's not there, I just haven't noticed it) but people running those Kill-a-watt meters have often reported different power consumptions on similar rigs with different motherboards. Sometimes by bigger margins than you'd expect. If the 3.3 and 5V rails aren't up to the requirements then the 12V output capacity is irrelevant as the system just won't run stably, if at all. Having that 8TB RAID array also draws from the 5V rail, btw, and it can be overwhelmed pretty quick if it doesn't have enough capacity.

Most people here when looking for a new PSU are going to look for the features they require in a reasonably informed manner. They will work out roughly what wattage they expect the unit to supply and in what configuration (single or multiple 12V rails), what connections they expect it to have, what efficiency rating they're prepared to pay for and how much "wank factor" they want (neons, UV reactive sleeving etc). Marketing hype plays little if any part in the decision making process, which is how it should be. At least I would assume this to be the case. You typical fanboi on the other hand will buy components on little more than the steaming BS fed to them by the marketing departments of our beloved hardware manufacturers and will usually get what they deserve.

Google is on record as proposing that all motherboards should be powered solely by a 12V supply. Any other required voltages could be handled onboard as required. The advantage here is that the PSU then becomes a single voltage unit, simplifying the design dramatically. This will allow PSUs to not only be substantially cheaper to build (that's why we have multiple 12V rails btw. The higher rated parts to build high output single rials cost far more than the parts needed to run multiple rails. Power components in particular cost a LOT more as current ratings increase while signal components for controlling the power switching are cheap) as well as being a lot more efficient.

[STEvil]

The multiple 12v rails are not actually multiple rails, btw. Most units tend to be a single +12v tap with multiple links rated at a given capacity, each being called a "rail". Thats why you have combined +12v rating. Some units do have true multiple +12v rails but they are less common and not as popular.

Using two true rails would mean double the parts of a single rail and efficiency ratings decrease as you add more parts generally. Less efficiency and more space used mean more heat and more expense plus harder to cram it all into the case.

I prefer a single +12v rail. Multiple links are ok as long as they can provide sufficient amperage, something some PSU's have an issue with.

[D_A]

I also prefer a single phat 12V rail, though on my budget I can't afford to be too snooty about it. With multiple rails I'm always concerned about voltage variations between components and circulating currents, particularly in data connections.

[STEvil]

You would get that even with a single rail.

[D_A]

It's possible, yes, though I would consider it more likely with multiple independent rails. I also prefer simplicity in power supplies. The less mucking around trying to be clever there is, the less chance of something going wrong. I honestly can't go past a simple well designed unit with high quality components. Elegance in all things.

[Panther_Seraphi]

I also prefer a single phat 12V rail, though on my budget I can't afford to be too snooty about it. With multiple rails I'm always concerned about voltage variations between components and circulating currents, particularly in data connections.

Sometimes its a good thing

Imagine the voltage drop on the 12v line when lets say a 460GTX sli rig goes from idle to full load in a game.

All components on that one line get the drop including multi rail PSU's the difference is that the multi rails have it a bit more gently due to the capacitance on each rail being seperated and not all together.

[Conquistador SW]

I would actually prefer a PSU with multiple rails as it is safer and most of the newest power supplies have one rail that is split to make a multiple rail PSU.
Especially for the high power PSU's like the 1000-1200W models it would be safer as JonnyGURU mentions in most of his latest reviews.

(A bit old but still an interresting FAQ : http://www.jonnyguru.com/forums/showthread.php?t=3990 )

[STEvil]

Sometimes its a good thing

Imagine the voltage drop on the 12v line when lets say a 460GTX sli rig goes from idle to full load in a game.

All components on that one line get the drop including multi rail PSU's the difference is that the multi rails have it a bit more gently due to the capacitance on each rail being seperated and not all together.

smaller components in the PSU will still result in similar drops, if not larger ones.