+12V rail reading too high?

[chrisexv6]

Opened my new Antec case (with SmartPower 2.0 500W PSU), and there was a smell coming from it! Unfortunately, to me, it smelt like burnt electrical (my wife, however, says Im nuts and that it just smells like new plastic).

So I decided to startup the PSU without connecting it to my new components. The readings on the lines are all "inline" except for +12V: under absolutely no load its at about 12.47V which isnt so bad. But once I had it physically in a PC (see below), it was idling around 12.7V. The reading was done with a multimeter connected into a spare molex power connector.

The PC i had it connected to is an old Athlon XP1200, on a Shuttle AK31 mobo with one optical and one hard drive powered up. So it doesnt utilize the second 4 pin power connector, nor does it utilize the extra 4 pins from the PSU ATX connector, and of course I didnt have a PCI-Express load either. Could this cause a higher voltage on the 12V line, because Im not really drawing anything from it? Or possibly because Im drawing more from the +3.3 and +5V rails (thats the only thing I could think of that might make the +12V reading go up after connecting to a mobo)?

I have an RMA from Antec, but the turnaround and shipping times are slow, it would take almost 2.5 weeks to get it back. Id hate to send it in if this is something that might be considered normal.

Thanks!
-Chris

 

[JTY]

I would RMA it.

 

[HybridHB]

My 510 deluxe reads 12.44 on my DMM and everything seems fine. I do think its a tad high though.

 

[chrisexv6]

OK, I guess RMA-ing it is.

What a way to start off my first build in 4 years.

-Chris

 

[Ice Czar]

you mean an Athlon 1200+ ? (actaully tha predates the + as well is just a 1.2GHZ) , thats a Tbird and with no 4 pin aux on the mobo
your only draw on the +12V is drives and fans possibly a PCI card that needs some

that supply is really geared toward a higher load and if your multimeter is in reasonable calibration and reasonably accurate thats too high

in a nutshell

chart by Oleg Artamonov @ Xbit


thus your "sweet spot" is outside of or on the edge of what that supply is really designed to do very likely, and its hard pressed to keep the stability out there

start here > http://www.xbitlabs.com/articles/other/display/psu-methodology_13.html
reading about crossload

here is an interactive gif of a not so great supply, where you can clearly see its "sweet spots" or range

you can see that too much or too little of a draw lays outside its "profile" the areas not in color so say you have 130Watts combined +3.3\+5V draw (up) and say next to no +12V (over) draw, of course thats the maximum draw so its from that point back over to nothing 0 and 0 on both scales

in a good supply you see a really large green range where stability is 1% thats a really good supply but anything within 5% meets spec, however how broad the various bands are and how well they actually match up with the dicated crossload area (as illustrated in the first gif in the 300 watt class for the various spec) is an indicator of its capability

alot of supplies dont fully cover a given spec's crossload
and might be just great for one config but a horibble match for backward compatibility
I think its likely thats whats going on here

 

[chrisexv6]

That was VERY informative, thanks! Im surprised I didnt land on that page during my surfing about the subject.

In your opinion, should I stick with this PSU or RMA it?

I too have a feeling that its just not *made* for an older setup (you are correct, its just a plain old Athlon XP 1200), but at the same time I dont want to risk frying all my new stuff. I might ask Antec tomorrow what they would expect to see on the rails with what I had hooked up, but most of the time opinions here and on other PC forums are much more reliable.

Thanks again!
-Chris

 

[jonnyGURU]

If you RMA it for another Antec, you're going to get another power supply that does the same thing as long as you plan on using it with that Athlon 1200+.

Antecs, among many other current design power supplies, have a crossload issue that is going to exhibit a high 12V and low 5V if there's little to no load on the 12V rail.

The solution is to either upgrade your motherboard (MSI and Abit boards regulate CPU voltage off of the 12V rail, for example,) change your platform (Pentium 4 or Athlon64) or get a power supply with "old school" specifications (TWV480 or most <= 400W PSU's on the market.)

 

[chrisexv6]

I apologize if I didnt specify..........this PSU will be used exclusively with an Venice 3000+ and a DFI LanParty mobo, so it will definitely be using the 12V line.

I only hooked it up to the Athlon to make sure it didnt fry anything before I hook it up to my brand new stuff.

Is it really a crossload "issue" with all of the Antec PSUs, or is it just a byproduct of the ATX V2.0 spec? Unfortunately I dont know anyone with an ATX V2.0 PSU, so I cant check for myself, but it sounds like I would see a high 12V line no matter what, until I connected it to a newer setup that utilizes the extra 4 pin connector, and/or a PCI express bus.

Thanks!
-Chris

 

[jonnyGURU]

I apologize if I didnt specify..........this PSU will be used exclusively with an Venice 3000+ and a DFI LanParty mobo, so it will definitely be using the 12V line.

I only hooked it up to the Athlon to make sure it didnt fry anything before I hook it up to my brand new stuff.

Is it really a crossload "issue" with all of the Antec PSUs, or is it just a byproduct of the ATX V2.0 spec? Unfortunately I dont know anyone with an ATX V2.0 PSU, so I cant check for myself, but it sounds like I would see a high 12V line no matter what, until I connected it to a newer setup that utilizes the extra 4 pin connector, and/or a PCI express bus.

Thanks!
-Chris

Well, let's put it this way. It didn't fry your Athlon 1200+. And the 12V reading isn't so high that if there was something wrong with it, it wouldn't fry any of your new stuff either. So just suck it up and plug the thing in. Take a look at the voltages and you're probably going to see the 12V at a more normal level.

Is it Antec? No. Is it the ATX12V 2.0 spec (not ATX v2.0, BTW)? In a way, yes. SMPS's rails are just naturally interactive. The load on the PSU almost needs to correspond with the specs on the label if you're to expect dead on voltages. Some power supplies behave better than others, but for the most part it's a non-issue once the PSU is installed in a machine that it was designed for.

The type of CPU makes the biggest difference because you're talking about either a 7A load on the 12V rail or a 16A load on the 5V rail for the same CPU depending on how that CPU's core voltage is regulated by the motherboard.

 

[Ice Czar]

The solution is to either upgrade your motherboard (MSI and Abit boards regulate CPU voltage off of the 12V rail, for example,) change your platform (Pentium 4 or Athlon64) or get a power supply with "old school" specifications (TWV480 or most <= 400W PSU's on the market.)

you forgot the best solution
add a bank of fans and a 10 drive RAID array
your not going to get a better excuse

but I do agree with your conclusions and solutions as always

I apologize if I didnt specify..........this PSU will be used exclusively with an Venice 3000+ and a DFI LanParty mobo, so it will definitely be using the 12V line.

I only hooked it up to the Athlon to make sure it didnt fry anything before I hook it up to my brand new stuff.

Is it really a crossload "issue" with all of the Antec PSUs, or is it just a byproduct of the ATX V2.0 spec? Unfortunately I dont know anyone with an ATX V2.0 PSU, so I cant check for myself, but it sounds like I would see a high 12V line no matter what, until I connected it to a newer setup that utilizes the extra 4 pin connector, and/or a PCI express bus.

Thanks!
-Chris

In that case I definately hold on to it until your able to get the +12V heavy system together
in the meantime try to get an idea of the calibration on the multimeter and use it to hook up the new system and take a reading, the mobo has a (VRM) Voltage Regulation Modual that will be able to easily deal with a power supply a little too high for a short period of time at least enough for you to measure, since there is a 3 year warrantee you can then RMA or you can trim the pot to get the rail inline

http://hardforum.com/showthread.php?t=765175

antec truepowers are very unique in that they dont have a shared regulation of the +3.3V and +5V rails like most other supplies, I would guess that supply is just fine and its mostly crossload, with a the rest of the odds on your DMM and a possibly misadjusted pot that has wondered at bit form shipping, temperature or just someone forgot to put a spot of glue on it