removing a computer PSU's 5V standby voltage (it confuses my KVM)

Standby voltage is usually there for a reason.

pin 14 (green wire) turns on the supply. Try connecting pin 14 to pin 15 (ground) and see if it the supply starts up. If it does, disconnect the standby Voltage and then then try to attach it to a PC and try to turn it on. If the supply doesn't run in a PC with pin 9 removed, the voltage is most likely needed to make the motherboard work properly

q_q snipped-for-privacy@yahoo.co.uk wrote:

connecting green and black(gnd). Well, i'd rather not have the PSU on permanently. And I think doing so would cause that. Albeit low power. I'll try just cutting purple first.

also, perhaps using 1 less GND wire may be problematic? Thre are so many GND wires for a reason. e.g. one wouldn't want to cut them all and use one. similarly, one wouldn't want to use one for something else.

I guess i'll have to try it.

I hope for a few more opinions confirming that cutting the 5vsb won't fry the mbrd or psu.

If it does, disconnect the standby Voltage

Plug the computer into a switchable power strip, and turn the switch off.

that is a no good solution. By that reasoning, I could switch it off at the PSU (switch on the back), or pull the power cord out. But no good.

Attempting the cutting purple wire solution- the only option

I just tried it on a dead MBRD with no processor, comp didn't seem to turn on. nobody fried. MBRD behaved as if the green and black were connected i.e. it turned on. And no 5V SB. I'll try it on a decent MBRD that I know turns on.

No, didn't work.

I tried it on the working MBRD, the PSU didn't turn on , so I attached the green and black. The PSU turned on, the comp turned on too, but the comp didn't sound like it was booting up . I didn't atach a monitor to check properly. Even if it did boot up, it's not what I want because the comp wouldn't turn off by the switch.

Somebody should make and sell an ATX power supply that works without the 5V SB.

That would defeat the purpose of an ATX PSU, and in turn would produce a non ATX compliant PSU.

In the other hand, the PSU is not the problem. The problem is the motherboard design. No ATX motherboard will work without the 5VSB line because it=B4s used to provide power to certain parts of the motherboard, like the RTC, part of the turn on circuit, and so on.

: :

Removing 5Vsb won't fry the mbd or psu. You just won't be able to turn on the PC which may not be what you want.

I would cut the 5Vsb wire and connect a switch to the cut ends so that I can easily "reconnect" 5Vsb to the ATX conn. on the motherboard. To make it convenient I would mount the new switch to the front panel. If you give up the RESET capability, and can find an ON/OFF switch in the same form factor as the RESET switch, you don't have to drill any hole in the front panel. You still need to solder the cut ends to extension wires and then to the new ON/FF switch. Actually, why not switch off the mains switch?

/bledge 29 Jun 2006

How about an electronic hack to remove the Ps2 and USB Wakeup. i.e. Particularly the 5V that comes out those ports while the Comp is powered down.

Some MBRDs and/or their BIOSs don't let you disable Ps2 wakeup.

That aspect of 5VSB is clearly not a necessity for an ATX MBRD to work. Many even let you disable it. The problem is those that don't.

I see, so I turn it on with the 5VSB, but then turn the 5VSB off once the comp is on, and you say that will work. I could try that.

Yes, that would work perfectly. You see, I am near the computer when I turn it on, but i'm typically far away from it when I turn it off. By your method, I can shut it down without driving my KVM(KVM Switch) haywire.

great idea, thanks. I had to read that twice. I see, it'd be a good position to place the "5VSB on/off switch".

I realise that I can't use the reset switch itself to switch the 5VSB on and off. Because it only holds the circuit together as long as it is held down. Infact, I reckon the power switch works the same. Because one only needs to jumper whichever 2 pins for a moment, and the comp goes on or resets.

It is turned on from near, but shut down from far away. I have a KVM(KVM Switch), and a KVM Extender. i.e. my computer box(es) are in one position of the house and i'm in another with my monitor keyboard and mouse.

Many Thanks for your idea. I'll be giving it a go.

This is very exciting! I like electronics projects. Even simple ones. I can't do complex ones, i'm only a computer techie - but i'm a computer techie with a multimeter and a soldering iron ;-)

Actually, I can't see it working. If Ps2 runs on 5VSB, then when the

5VSB is off, it won't get the 5V it needs. It surely won't just swap over to the 5V rail.

I suppose i'd either have to - *somehow* amend the MBRD's ps2 thing to take the standard 5V instead of 5VSB. Or, -*somehow* remotely turn off 5VSB before turning the computer off. Or even after turning it off. I wouldn't know how to go about either. I suppose I could crack open the metal casing behind the ps2 connector, and see if I get any ideas. Or - steal/use/cut the 5v wire from a 4 pin molex connector, thread it out a hole in the case and into a ps2 cable that is plugged into my comp's ps2 port. So "5V of 5VSB" will be coming out the ps2 port, down the ps2 cable, then a wire of the ps2 cable will be cut, and will continue with regular 5V. Sounding a bit comical now. I suppose i'd have to ground that end of wire receiving "5V of 5VSB" too.

comp

Actually, no need for me to do any of that. I think it's only one funny computer whose ps2 wakeup won't disable. I will apply a similar technique to the one you mention. I will put a 5VSB switch in , but not mounted at the front. The switch will extend into my room. immediately Before or after I turn the computer off, i'll turn the 5VSB off.

I'll use shielded cable, so it doesn't act as an aerial. (I'm 20M away from the box)

I'm not big on these things but I think 18 or 20AWM (thickness) like an AC/DC adaptor wire thickness. Should be Dual wire, not strands. So i've got 2 nice copper things going through. Should be shielded cable. (I once tried extending teh switch of my KVM. I didn't use shielded cable, and it had problems. apparently the wire acted like an aerial. So i'll use shielded cable to prevent that. I'll ground the shield wire of the cable on the comp case).

Thanks for giving your idea. I wouldn't have had this idea without it.

-----8 You see, I am near the computer when I turn it on, but i'm typically

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