PSU/MSI D.O.T. Motherboard HELP PLEASE (-5V pin???) - Techist - Tech Forum

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Old 07-20-2005, 04:22 AM   #1 (permalink)
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Unhappy PSU/MSI D.O.T. Motherboard HELP PLEASE (-5V pin???)

Hi to all,

My predicament revolves around my new motherboard [MSI K8N Platinum SLi] and PSU [Hiper HPU-4S525 (24pin ATX)].

Having put together all the relevant parts to assemble my own PC, I came to building it all up yesterday.

However, when I came to plumbing in the PSU, I noticed that the motherboard manual stated in a highlighted paragraph at the bottom of the ‘PSU connectivity’ page (quoted exactly as printed):-

• Power Supply of 450watts (and above) is highly recommended for system stability [not an issue as my aforementioned PSU is 525 watts]
• For ATX 12V power connection [I assume this is referring to the 4 pin CPU 12V power connector?] it should be greater than 18A [I assume this means 18A or more? And if I’ve understood it correctly my new PSU is 17A]
• For this model [of motherboard] you must use the power supply that with a -5V pin supply [again, the assumption being that your PSU must have the -5V pin connected, & BTW the emphasis of ‘must’ is in the original]

Now this where I’ve come unstuck!

In the past several weeks of trawling websites (manufacturers & retailers) I haven’t once come across any emphasis towards certain PSU’s having/not having this all important -5V pin connection, so when I came to buying my PSU two weeks ago it wasn’t a concern that even occurred to me, nor was it raised at the point of purchase when I enquired as to the suitability of a number of PSU’s (and the retailer gave me plenty of details).

Well, when investigating my PSU, I discovered to my frustration that this -5V pin WASN’T connected!

Moreover, I checked the two other 24pin ATX PSU’s in the house (my kids and my wife’s PC’s respectively) and neither of those have this pin connected either.

So then, I phoned a pal who’d built a couple of his own PC’s and who’d been an invaluable source of help while I was putting together mine, and asked him about this and to my surprise even he’d never come across the significance of PSU’s having/not having this -5V pin! In fact, he went and checked his PSU (in a PC that he’d built himself) and discovered his DIDN’T have this -5V connection as well.

So I need to identify a few things.

Firstly, why isn’t this relevance highlighted anywhere if it is supposedly so important for specific motherboards? I mean when anyone buys a PSU it doesn’t ever seem to be emphasised that certain PSU’s have/don’t have this -5V connection (or, indeed, if certain motherboards need/don’t need it), so what’s to stop someone buying a PSU that DOES have this connection and using it with a motherboard that doesn’t support it? Wouldn’t it damage it? And why do certain motherboards NEED this connection when it seems a majority of PSU’s are manufactured WITHOUT this pin connected? How can you tell if a certain PSU does have this pin connected as many sites don’t mention this particular detail in their specs?

Secondly, how on earth do you find out if a PSU has a 4 pin 12V ATX supply that’s over 18A. I haven’t come across one retailer that supplies such info on their site, and only a very few manufacturers seem to detail this and even then only in a rather vague way. How can you be certain that the PSU you buy is as specific as this one MSI are stipulating for use with their motherboard.

Thirdly, does anyone else use this motherboard, and if so, what PSU(s) do you recommend?

Being far from any type of expert, I really expected a new PSU of 525 watts to be perfectly ample for contemporary motherboards, but now I’m faced with the situation that my new PSU is incompatible with this MSI motherboard, when no-one even drew any attention to the fact that PSU’s/motherboards need/don’t need such a specific type connection!

I mean how important is it that my PSU HAS this -5V connection and a 12V 18A supply? Would my motherboard be damaged if I didn’t use the -5V pin and only the 17A supply?

Can anyone educate me and get me out of this mess? My sincere thanks in advance for any help offered.

Best wishes to all.

LAGAVULIN
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Old 07-20-2005, 12:06 PM   #2 (permalink)
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Just to add more confusion to this-

After been into work today (I work in the field of IT), I asked the staff IT/PC technician about this and even he hadn't come across the significance of this -5V pin He added that the PSU should work perfectly fine and that this non-connected pin shouldn't cause a problem whatsoever

Moreover, I spoke with the Tech Support dept of the retailer of my PSU and they said exactly the same thing - that NOT having this -5V pin connection wouldn't make any real difference to the performance of the motherboard and that it would be perfectly compatible :amazed:

Of course this is in complete contadiction of the manual, so are they right? If I wasn't confused before, I am now!

Thanks for reading.
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Old 07-20-2005, 12:33 PM   #3 (permalink)
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-5 volt is used for old ISA cards and is not needed at all in modern PC's

And, the 12 volt ATX connector is only rated at 8 amps, they are probolly just recomend a PSU with 18 amps on the 12 volt rail to run the PC

Even my 420 watt cheaper thermaltake power supply even has 18 amps on the 12 volt rail in total...

In conclusion, don't worry about the -5 volt rail at all, unless your using ISA cards (which you cant with a newer motherboard like yours)
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Old 07-20-2005, 01:59 PM   #4 (permalink)
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Quote:
Originally posted by DJ-CHRIS
-5 volt is used for old ISA cards and is not needed at all in modern PC's

And, the 12 volt ATX connector is only rated at 8 amps, they are probolly just recomend a PSU with 18 amps on the 12 volt rail to run the PC...

...In conclusion, don't worry about the -5 volt rail at all, unless your using ISA cards (which you cant with a newer motherboard like yours)
Many thanks Chris.

Your answer does back-up what others have said (as mentioned above).

But it is still very confusing that MSI consistently stress [on several documents that come with the board] that you MUST use a PSU with the -5V pin with this motherboard

Could it be that MSI have put something on the board that necessitates this -5V pin? Or as you suggest, would that be implausible as such technology needing -5V isn't even used anymore?

A big thanks Chris,

LAGAVULIN
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Old 07-20-2005, 05:32 PM   #5 (permalink)
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Well if they really did require a -5 volt pin, I would think I would be hearing of at least one MSI motherboard compatability issue.

Worst comes to worst, you need to find a new power supply
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Old 07-20-2005, 09:42 PM   #6 (permalink)
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That is strange..... Oh well hook every thing up and it should work.... Still strange one of there manuals has that.....
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Old 07-21-2005, 04:38 AM   #7 (permalink)
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Thanks guys for your replies. Below is the main part of a response I received from another forum, which seems to sum up the issue:-

-----------------------------------------------------
Looking into it, it seemed to only effect MSI motherboards, and it's the on-board sound that requires it. If the -5v is missing, then either the sound won't work, or it gets distorted...Having said that, there seem to be people with your motherboard that have no problem using PSU's with no -5V...

Links discussing the -5v on MSI boards below:

http://www.hardforum.com/showthread.php?t=869196&page=3

http://diamondclub.msi.com.tw/eng/fo...hlight=&page=2

------------------------------------------------------

If anyone else has been as confused as me, then this should shed some light on this strange situation,

Regards to all,

LAGAVULIN
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Old 07-21-2005, 12:11 PM   #8 (permalink)
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I dunno my onboard sound cant be used to its full potention because im using a car amp powering car speakers to get sound. So i dont notice a differnce on my msi board.
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Old 07-22-2005, 05:24 AM   #9 (permalink)
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Unhappy Need more advice...

Hope some of you more experienced people could help me out here.

Continuing on from the above issues, I'm having a really odd problem with this new MSI K8N Platinum MoBo and seemingly my installed RAM (Samsung DDR400 PC3200 Single-Side 512mb and 256mb respectively).

Y'see, the MoBo came with a "D-Bracket2" which is a front PCI style slot that cables into the MoBo, but it has the additional feature of combining 4 LED's that attach to the MoBo and act as a 'diagnostic' tool. Simply, the LED's light up in different combos to highlight any particular issues with the system.

Well, the newly built system - on very first boot-up - kept hanging at the D-Bracket LED indication of "memory detection", which the manual describes as meaning that either the RAM is damaged or not installed correctly.

This happened several times and I got nowhere, but somehow it decided to kick-in at a later attempt Nevertheless, with Windows being booted on a new MoBo it detected 'new hardware' and I had to even restart/reboot a few times with NO problems whatsoever.

When done, I turned off the PC for around and hour, and then went back to it to do a little more work, and it now refuses to boot again, repeating the exact same problem of the system hanging at the D-Bracket LED indication of "memory detection".

This seems weird as the RAM, although NOT listed in MSI test reports, works in my other shop bought PC with a MSI MoBo, and it DID work for a short period in this new MoBo (after initially refusing to be detected).

So what do you think this problem is caused by? Is it the RAM that is simply incompatible and just works haphazardly, or do you think this is a prob with the MoBo?

Please advise as this is really starting to send me insane

Best regards to all,

LAGAVULIN
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