S12-330 has bad -5V line --- should I worry?

adrianmariano · Post by **adrianmariano** » Wed Aug 22, 2007 6:52 pm

I got an S12 II 330 W to replace a 8 year old power supply in an 8 year old machine (pentium III 500 MHz). The old power supply was loud and getting quite a bit louder of late (fan bearings probably dying).

When I booted with the S12 the BIOS halted and said there was a power fault. I went and looked at the monitor and it says the -5 V line is -6.2 V, which is kind of far off. I have a S12 380 in my other box and tried to check it but the motherboard evidently doesn't care about the -5 V line as it doesn't report it at all.

So should I send this power supply back? Should it bother me that the -5 V line is so far off? I'm typing this from the affected machine and it hasn't started smoking yet....

Post by **MikeC** » Wed Aug 22, 2007 8:41 pm

There has been no -5V line on any ATX12V PSU since before ATX12V v1.3 -- which goes back some 5 years. There hasn't been a -5V line on any PSU reviewed by SPCR since.... let's have a quick look.... a Nexus 3000 in Oct 2002.

-5V was used on some of the earliest PCs for floppy controllers and other circuits used by ISA bus cards. It was provided, in low current level (less than 1A), for compatibility with older hardware.

I bet your system doesn't need it -- just ignore the warning or turn it off; you'll get it with any decent quality PSU less than 5yrs old.

adrianmariano · Post by **adrianmariano** » Thu Aug 23, 2007 4:31 am

After I posted here I was looking through the manual that came with the new power supply and I noticed that it doesn't supply a -5V line, as you note. So it's unlikely that anything in this machine actually needs the -5V? (Not even the floppy?)

If I'm not confused about the source of the noise the SS12 II - 330W is a LOT louder than the 380W model I have in my other machine. Is this normal?

Post by **MikeC** » Thu Aug 23, 2007 7:13 am

adrianmariano wrote:After I posted here I was looking through the manual that came with the new power supply and I noticed that it doesn't supply a -5V line, as you note. So it's unlikely that anything in this machine actually needs the -5V? (Not even the floppy?)

Probably not, but it's easy enough to try the floppy and see whether it still works ok.

If I'm not confused about the source of the noise the SS12 II - 330W is a LOT louder than the 380W model I have in my other machine. Is this normal?

That does not compute. At idle, especially, there should be little if any difference. Also, the fan noise to power load curve is no different than before up past 200W... so I think you need to examine noise sources more closely to determine the reasons for the differences between your PCs.

alglove · Post by **alglove** » Thu Aug 23, 2007 4:04 pm

Adrian, if it makes you feel any better, I have an Abit BM6 motherboard running just fine without the -5V rail... floppy and all. This motherboard is also 8 years old. The original CPU was a Celeron 433.

In terms of actual usage, I think the -5V rail was already history long before this motherboard came out.

adrianmariano · Post by **adrianmariano** » Fri Aug 24, 2007 4:25 am

Ok. I'll run happily with no -5V rail. (The trouble with testing the floppy is that I'd have to find one first...)

Regarding the noise level, I did a careful investigation. I powered up with the hard drive and cpu fan unplugged and the noise level seemed reasonable, and similar to the 380 W supply in the other machine. I tried again with the hard drive plugged in and there was a slight increase in noise. I then plugged in the CPU fan and there was a tremendous irritating whine. When I closed the case up the whine seemed to lose its high frequency components, but I think the CPU fan was still the dominant noise source.

I don't know what caused me to believe that the power supply was loud before. (I had unplugged the CPU fan then too.)

Any recommendations on a quiet, not too pricey cpu cooler for a pentium III 500?

alglove · Post by **alglove** » Tue Aug 28, 2007 3:44 pm

What type of Pentium III 500 is it? It is a Slot 1 CPU, or is it a Socket 370? Does it use a Coppermine core? If it is a Socket 370, it will use a Coppermine core for sure. That will have a thermal design power of 13.2 W, which is astonishingly low by today's standards (see http://processorfinder.intel.com ).

If you are buying new, just about any Socket A heatsink will do. Sockets A and 370 are close enough that you can often use the heatsinks interchangeably, though you may want to make sure that you have enough room around the socket for the heatsink to work. To make it quieter, you can undervolt the fan. If you have enough airflow in the case, you can even do away with the fan completely and run the heatsink passively.

At 13.2 W, it does not take much to cool this CPU.

adrianmariano · Post by **adrianmariano** » Wed Aug 29, 2007 4:33 am

It is a slot1 Pentium III. Is there some way I can tell which type it is?

I was hoping to perform a thorough heatsink cleaning over the weekend, but I didn't get to it. However, I did upgrade the OS which made it possible to read the temperatures reported by the motherboard.

Do systems use tons of CPU power when you're sitting in the bios config options looking at the temperature readouts? Because the CPU always gets listed at 70 when I'm in there. And when I look at it (an hour) later from the OS I see values more like 40-50.

At the moment the only air flow in the case is due to the power supply fan. I could add a small fan (not sure if it's 80mm or bigger) to the case which would probably be easier than adding such a fan to blow right on the cpu heatsink.

Post by **MikeC** » Wed Aug 29, 2007 4:54 am

Check here: http://users.erols.com/chare/elec_pentium.htm#intel

There's only one P3-500 slot CPU listed. It's a katmai core, rated at 28W TDP. IRRC, the stock HS was almost entirely encased in plastic, with a ~60mm embedded fan in the center, airflow venting out on either end. A cleaning would probably help a lot. Another case fan would probably help too, but only if and the fan grill and the intake vent for the case are decently open
Older systems often loaded the CPU at least some -- maybe 70%? -- in open BIOS.

adrianmariano · Post by **adrianmariano** » Wed Aug 29, 2007 5:14 am

I checked the list and that looks like the right one. The 90 C heat limit is right. Your description is on target as well. It looks like a black plastic box with a fan in the middle. (What's the deal with encasing a heatsink in plastic?) Since that little fan is noisy I'd like to get rid of it (or quiet it) somehow.

The case is fairly closed. I think there is some venting around the speakers at the front and there are vents underneath opening out to the floor.

Post by **MikeC** » Wed Aug 29, 2007 5:45 am

adrianmariano wrote:I checked the list and that looks like the right one. The 90 C heat limit is right. Your description is on target as well. It looks like a black plastic box with a fan in the middle. (What's the deal with encasing a heatsink in plastic?) Since that little fan is noisy I'd like to get rid of it (or quiet it) somehow.

The case is fairly closed. I think there is some venting around the speakers at the front and there are vents underneath opening out to the floor.

With that heatsink design, the only thing other than its own fan speed that might impact CPU cooling is the temperature of the air around it. If you just slow the fan on the HS down, the CPU will run hotter. And unless there's some kind of decent access to outside air, a back panel case fan won't really do much to cool down the air around the CPU. Worth a try, but I would not hold my breath.

If the heatsink fins were more exposed, then cooling would be more affected by the surrounding air temp/flow. But, again IRRC, to complicate matters, the plastic casing actually holds the CPU/HSF assembly altogether. You can't just crack it open and run the CPU/HS bare.

Globalwin, Alpha and a couple others used to make some massive slot 1 heatsinks. Like - http://www.pcstats.com/articleview.cfm?articleID=656 and http://www.alphanovatech.com/cat_pf2e.html If you can find one of those golden oldies, you're laughing. The alpha site states they may have some oldies...

adrianmariano · Post by **adrianmariano** » Wed Aug 29, 2007 5:53 am

I saw this design of heatsink: http://www.directron.com/genslot1fan.html It has exposed fins.

But if the plastic case actually holds everything together then it makes things more complicated. (I obviously need to get this sucker open and take it apart so I can see what I have to work with.)

Those alpha heat sinks are pretty impressive. And with two fans! Wonder how much noise they make.

Post by **MikeC** » Wed Aug 29, 2007 6:04 am

adrianmariano wrote:I saw this design of heatsink: http://www.directron.com/genslot1fan.html It has exposed fins.

But if the plastic case actually holds everything together then it makes things more complicated. (I obviously need to get this sucker open and take it apart so I can see what I have to work with.)

Those alpha heat sinks are pretty impressive. And with two fans! Wonder how much noise they make.

Hunt around on the web for instructions on how to safely remove the stock HSF. It's a bit tricky. The HSF you linked isn't great. Just a small piece of extruded aluminum. Remember, the Alphas was made for oc'ers. I'd forget about those fans and find a way to attach a BIG slow fan (80~120mm) over the whole assembly.

adrianmariano · Post by **adrianmariano** » Wed Aug 29, 2007 6:18 am

Well, it's got exposed fins unlike the existing heatsink.

Someone else mentioned a fan mounting bracket that screws on to the PCI card slot and would be able to hold a fan over the heatsink.

http://www.endpcnoise.com/cgi-bin/e/std/sku=fb123

In fact, this particular vendor specifically suggests it for slot1 cpus. (But if the heatsink is encased in plastic it seems like it wouldn't be entirely sufficient.)

Post by **MikeC** » Wed Aug 29, 2007 6:23 am

adrianmariano wrote: (But if the heatsink is encased in plastic it seems like it wouldn't be entirely sufficient.)

Not at all. You can also fudge something perfectly workable for no $$ -- see the pics in the section on Replacing the Stock Retail Fan on p5 of my first DIY PC article >5 years ago: Silencing a P4-1.6A oc'd to 2GHz

adrianmariano · Post by **adrianmariano** » Wed Aug 29, 2007 6:35 am

I'm really going to have to take a close look at my setup before I can appreciate the options. It looks like on the page you referenced you took out the fan and replaced its frame with wood shims so that the heatsink would still lock down. But your heatsink was oriented so that air from above would travel between the heatsink fins.

If my heatsink is encased in plastic that can't come off, and oriented the other way, then air from above wouldn't do a whole lot of good.

I also couldn't tell how you had those fans mounted in your system. They look kind of like they're just resting on top of the system.

Post by **MikeC** » Wed Aug 29, 2007 6:43 am

adrianmariano wrote:I also couldn't tell how you had those fans mounted in your system. They look kind of like they're just resting on top of the system.

This was the only part I was referring to.... and...

...the text that describes it is on page 3 -- http://www.silentpcreview.com/article14-page3.html:

NOTE the metal piece used to suspend the fan over the chip and the video card. It's a PCI slot cover that gets taken off the back of any case whenever you use a slot. Modified with a hole drilled at one end for the single screw that holds the fan. A little bending, and twisting, and then tightening of the screws is all that's needed. My poor man's Zalman-style fan bracket.

adrianmariano · Post by **adrianmariano** » Wed Aug 29, 2007 6:58 am

That's a good tip. I wouldn't have expected this mounting system to be adequate. (Shows what I know!)

adrianmariano · Post by **adrianmariano** » Thu Aug 30, 2007 5:18 am

I took a closer look at my system last night, but this all has nothing to do with the power supply (no problems yet with the -5V) so I've done the right thing and posted the details in the forum on cpu cooling where I had actually started a different thread on this topic.

viewtopic.php?p=364870#364870

VanWaGuy · Post by **VanWaGuy** » Thu Aug 30, 2007 7:45 am

I am glad that I stumbled over this thread. I have seen crazy numbers in some of the motherboard monitor programs that list a -5V number, but they have seemed like random numbers.

gforcefan · Post by **gforcefan** » Thu Aug 30, 2007 8:44 am

This is such a coincidence it is scary. I was going to post the same question today.

My sister's psu went this weekend, I just replaced it with an antec earthwatts 380 - cause a local store had it on sale for $30!

When I booted up, got the same -5v error. Told motherboard to ignore.

Her system - PIII 500 slot 1 with asus p2b mobo.

twilight zone