The Power Supply Thread

[starwars7]

Originally posted by: jonnyGURU
It turns out that the rear fan of the chassis was causing a vacuum. A venturi effect, if you will. The fan was moving so much air that it was sucking air away from the PSU. The solution was to add a fan to the front so the chassis would have positive pressure

Wow nifty, I hadn't though of that, but it makes a lot of sense.

 

[GalvanizedYankee]

starwars7, on a typical ATX case it might be easyer to mod paired low speed 92x25s
on the lower front of the right side cover. That way dealing with wiring is not a hassel as it can be on the left side cover. As long as the room is vacuumed every two weeks and the rig is 12" off the floor, dust should not be a serious problem.

With some cases getting a fan fitted to the front means rig disassemly and the restiction of doors or decorative grill work.

Just a thought.


...Galvanized

 

[jonnyGURU]

Originally posted by: GalvanizedYankee
starwars7, one a typical ATX case it might be easyer to modded paired low speed 92x25s
on the lower front of the right side cover.

Probably the most practical "side panel mod" you could do. :thumbsup:

Front fans are often a pain to install, are difficult to keep clean or even remember to keep clean and are restricted by the front bezel.

 

[Bobthelost]

Originally posted by: jonnyGURU
But you say that going into the thermal-dynamics of chassis ventalation is off-topic, yet it directly addresses the point you're trying to make. You brought it up, I give you my reasoning and it's off topic?

More that it's starting to edge off topic going into depth on it here. While including a fudge factor without referencing why it's there is misleading, which was what my point was refering to.

This is to be a FAQ for PSUs, a required reading or a primer. As such it'd be fair to say "these numbers are including a fudge factor for higher temperatures, in some circumstances and with some brands these aren't nessisary, but these are the exception rather than the norm"

Or better yet remove that aspect of the fudge factor and state that PSU temperature is important, and to remember that higher intake temperatures will result in a lower output power, so adding a couple of amps would be a good idea. That way you leave it up to the person reading to work it out.

As to my writing style, you'll either get used to it or you won't. It doesn't bother me that much. Having said that you'll notice when i'm getting annoyed as there'll be lots of ****s in my posts, otherwise assume i'm just being blunt.

 

[jonnyGURU]

Well this is what I added/edited:

Now keep in mind that these numbers are VERY liberal. All of the numbers are PEAK and in the case of different clock speed CPU's or GPU's within the same "family," I just used the highest number possible. This is because I can't possibly address every possible scenario of thermaldynamics and chassis layout that each and every one of you guys may have. I'd rather judge on the side of caution and just suggest that you have "more" power available, rather than "just enough." Truth be told, you might be able to get by with as little as 75% of what you may have calculated. But that might only apply to you and not everyone else here. Just keep in mind that more than anything else, this post should convey to you the importance of the 12V rail in a modern system and prevent you from buying one of these "480W" power supplies with only 18A on the 12V rail!

It's not specific enough to muddy the waters, but I think it conveys my intentions.

Now lets get back on topic.

 

[theMan]

i think i may be having some power issues, but im really not sure. sometimes, while i am gaming, the monitor goes black, and i have to restart. this happens just occasionally. however, once when it happened, i thought i heard my fans slowing down right before.

here are the specs for my psu: http://www.seasonicusa.com/products.php?lineId=4 its the super silencer 400w.

and, my rig is in my sig.

 

[jonnyGURU]

Originally posted by: theman
i think i may be having some power issues, but im really not sure. sometimes, while i am gaming, the monitor goes black, and i have to restart. this happens just occasionally. however, once when it happened, i thought i heard my fans slowing down right before.

here are the specs for my psu: http://www.seasonicusa.com/products.php?lineId=4 its the super silencer 400w.

and, my rig is in my sig.

May not be a PSU issue at all. The PSU should be more than enough for your build.

You're moving a lot of air in that case, so your temps should look good, right? Your voltages look good too? Touch the side of the PSU when it does this shut down, is it hot to the touch? Leave the side panel off of the case, does the problem go away or does it duplicate itself?

If the problem persists, I'd be more willing to think there's video card or motherboard issue here.

 

[theMan]

well, everything in my case is very cool, side of the psu is cold to the touch. it really isnt too much of a problem, its only happened about 3 times in 2 months. my voltages seem ok, according to mbm5, but my 3.3v is a bit low, 3.11v but, im not sure how accurate that is. 12v is a 11.96v.

 

[jonnyGURU]

Originally posted by: theman

...My voltages seem ok, according to mbm5, but my 3.3v is a bit low, 3.11v but, im not sure how accurate that is. 12v is a 11.96v.

Which brings us to the next part....

Testing Power Supply Voltage with Software

(Quoted from a forum post by jrtm) Testing your power supply with software will give incorrect readings. So although the monitoring software may look fancy and appear to be intricate in its function, it is really an almost useless piece of eye candy. Monitoring power supply voltages with software is about as useful as a stethoscope to a garbage man.

There's one chip on the motherboard that manages health monitoring (typically referred to as the "Winbond chip" because the chip is typically made by Winbond.) Software gets it's readings from the same chip the BIOS does, so to say readings from the BIOS would be more accurate would be a falsehood. The margin of error on this chip is pretty great because it needs to be taken into consideration where this chip gets it's data (the ATX connector) and the resistance created by the traces between the ATX connector and the chip.

Software isn't COMPLETELY useless: If readings are WAY OFF, there may really be a problem with the power supply. But always double check the ATX connector to the motherboard first. If for some reason the connector is not plugged all of the way in the board, the resistance from the loose connection can cause low voltages.

And never pay any mind to the -5V or -12V reading in software. Those are typically EXTREMELY off simply because most power supplies have no -5V lead and most motherboards don't use the -12V lead!

To test your power supply voltages in the most basic of ways you are going to need an electronic device called a multimeter, which you physically will have to plug into the connectors on your power supply. Of course, you will need to know what leads are what. Yellow is typically 12V, red is typically 5V and orange is typically 3.3V. If you put your multimeters red probe to the tip of any one of these leads, and the black probe to a black wire (any will do as a power supply's grounds are all common) then you can get an accurate reading of your voltages.

 

[jonnyGURU]

Testing a power supply without a computer...

ATX power supplies DO NOT turn on when you flip the switch in the back!!!

An ATX power supply is always "live", even when it's "off", when it's plugged in and it's rear switch (if applicable) is switched on..

The +5V standby is always coursing through your motherboard whether your PC is on or not. This is how the CMOS keeps it's settings with or without it's CMOS battery and wake on LAN, wake on ring and keyboard power on is accomplished.

The power supply is instructed to energize the other power leads throughout the system when the "Power On" lead (the green wire on the main connector) is grounded. Without grounding the green wire on the power supply, you will not be able to test ANY of the power leads on the power supply except for the +5V standby.

To test the power supply, you can do this: Unplug the power connector from the motherboard. Connect ("bridge") the green and black wires on the power connector together with a paper clip or a piece of wire. This will energize the power supply. Now, using a multimeter, the 12V should read 12V, the 5V should read 5V and the 3.3V should read 3.3V (within +/- 5% per Intel specifications.)

 

[hytek369]

wow, this is a great thread, thanks

 

[rise]

how important is it to have the graphic card on its own dongle for those without a pci-e connector?

i have a dfi nf4 board that asks for a 4 pin molex and a floppy connecotr to the mobo (in addition to the main 24 pin and 4 pin atx.)

i need to use two 4 pin molexs to make a pci-e connector.

if i only have two dongles with 4 pins molexes, should i run my opticals on the dongle with the mobo or run them on the dongle with the graphics card?

i would think running the mobo and the graphics card on the same dongle would be the least ideal power wise, even if it would be the best aestheticallly (sp?) and convenience wise.

 

[jonnyGURU]

Originally posted by: rise4310
how important is it to have the graphic card on its own dongle for those without a pci-e connector?

i have a dfi nf4 board that asks for a 4 pin molex and a floppy connecotr to the mobo (in addition to the main 24 pin and 4 pin atx.)

i need to use two 4 pin molexs to make a pci-e connector.

if i only have two dongles with 4 pins molexes, should i run my opticals on the dongle with the mobo or run them on the dongle with the graphics card?

i would think running the mobo and the graphics card on the same dongle would be the least ideal power wise, even if it would be the best aestheticallly (sp?) and convenience wise.

Your best solution would be to run as few peripherals on the same lead as possible. As loads increase, so does resistance and voltages drop.

You would want to split the motherboard connector up onto a different connector from the video card, but I'm not sure the optical drive is the best thing to split off. What's going to happen when that drive spins up when you put a new disc in the drive?

Of course, if you only have two leads.. your proposal is the best solution.

 

[GalvanizedYankee]

I did read 70% of the dated PSU thread at HardForums. "poop in a box and put a wire in it"

Why is an ISO cert. held is such high reguard.?

Has there been any serious move to standardize PSU specs so the end user is not so easily fooled.?

Yes, I know of and have read some of what formfactors.org offers but aside from meeting that spec
there is no truth in advertizing.

I know that gives you something to do but it would be nice if all the PSU suppliers were on the same page.


...Galvanized

 

[jonnyGURU]

Originally posted by: GalvanizedYankee
I did read 70% of the dated PSU thread at HardForums. "poop in a box and put a wire in it"

Why is an ISO cert. held is such high reguard.?

Has there been any serious move to standardize PSU specs so the end user is not so easily fooled.?

Yes, I know of and have read some of what formfactors.org offers but aside from meeting that spec
there is no truth in advertizing.

I know that gives you something to do but it would be nice if all the PSU suppliers were on the same page.


...Galvanized

Agreed!

In fact, I have a friend whose boss wants to start a class action law suit against all of the power supply companies that don't put "correct" information on their labels/documentation.

The problem is, every power supply has a caveat. It may not be easy to find, but there's a caveat somewhere! Like really low lab temps, 10% rail tolerance and the most common, peak vs. sustained (even though peak only has to hold for a minimum of 500msec to be considered peak even on a very good quality power supply!)

It's sad.

 

[rise]

Originally posted by: jonnyGURU
Your best solution would be to run as few peripherals on the same lead as possible. As loads increase, so does resistance and voltages drop.

You would want to split the motherboard connector up onto a different connector from the video card, but I'm not sure the optical drive is the best thing to split off. What's going to happen when that drive spins up when you put a new disc in the drive?

Of course, if you only have two leads.. your proposal is the best solution.

yeah. thankfully i use alot of no cd patches so the drives don't get alot of use. most of my ripping is done on my sons machine. and my hdd's are sata.

well, whats done is done, the psu will be here friday i think

i'll see how it goes. worse case is i just use it in my sons machine that doesn't require the pci=e connector.

 

[Boyo]

Okay. I am a member of the PSU challenged crowd. In other words, I read everything and I still don't know which PSU to purchase. First time builder, and maybe the last the way things are going.

Can ANYONE pleeeeze recommend a PSU. I get answers from anywhere between 500w to 650w. I just want to buy one, and feel safe.

I have been going back and forth with the Enermax Whisper 2 535w & the Enermax Noistaker 600w......

This is my hardware list:
NZXT Lexa (3x 120mm & 1x 80mm fans)
AMD X2 4400+
Asus A8N32-SLI Deluxe mobo
2x eVGA Geforce 7800GT 256MB
2x Seagate Barracuda 7200rpm 160GB Raid 0
Lite-On DVD/CD Burner with Lightscribe
generic floppy, monitor, keyboard, mouse, etc.

 

[jonnyGURU]

Originally posted by: Boyo

I have been going back and forth with the Enermax Whisper 2 535w & the Enermax Noistaker 600w......

I'm not sure there's enough difference between the two to make it a "tough decision." Both have 18A on each of two 12V rails. Although I don't know if the combined 12V max wattage is the same on both.

I'm not sure 18A per 12V rail is enough for a pair of 7800GTX's. I'd like to see 20A on one of those rails. Like an 18A/20A or a 20A/20A. Something with 420W or 444W on the combined 12V rails.

 

[Boyo]

How do you like the Antec TruePower 2.0 550w??? Am I getting closer at least?

 

[jonnyGURU]

Originally posted by: Boyo
How do you like the Antec TruePower 2.0 550w??? Am I getting closer at least?

I'm not at liberty to say what I like and don't like. I don't think this should be a "help me pick my PSU" thread either. This thread is to help you pick your own PSU.

The Antec has 19A/19A on the 12V rails.

Read the information I provided (specifically the "Watts Don't Mean Squat" post, the "Why do they split up 12V rails" post and the "Calculating how much juice you need on the 12V rail" post and do the math. I know you said you read the whole thread, but I think you might have missed quite a bit of the important information.

 

[Boyo]

Okay. I didn't mean to offend.....Thanks for your help.

 

[KoolDrew]

Awesome post! Very informative!

 

[jonnyGURU]

Originally posted by: Boyo
Okay. I didn't mean to offend.....Thanks for your help.

No offense taken. I just want this thread to stay on topic, unlike what happened to it Saturday, and not get into choosing specific model power supplies for people.

 

[JEDIYoda]

Nice thread!! Excellent information!!
In my opinion johnnyGURU this thread should be locked and then unlocked to allow you to update the thread.

Its obvious that people still have there own opinions even when presented with well thoughtout facts.

We could go in depth with that but suffice it to say...
Perhaps or maybe the MOD`s can give you the ability to unlock your thread as updates become apparent.

I for one thank you for taking the time to organize and write this thread!!

Time to LOCK the thread.....so as not to become a please pick a PSU thread.....

:thumbsup:

 

[metalstorm203]

If a video card has an auxillary power connect, does it take 100% of its juice from it when it's hooked up?