OT Confused over psu

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I've just installed a nice shiny, new 900w psu - it went on then I turned
off now it has stopped working!!!

I'm in the UK but the psu came with a US/Euro plug - are te voltages
different on psu's?  It powered on once with a uk 3pin power lead.


Re: OT Confused over psu

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WTF are you buying a 900W PSU for?


Who the fuck said I was trying to endear myself to anyone?

Re: OT Confused over psu

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forgot to say - its a tagan tg900-95 900w - sometimes powers up most times
not.  Have tried old psu which powers up evertime.

Re: OT Confused over psu

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Could be this one:


What motherboard are you plugging it into ?

Are you operating it with a load connected ?

Are you meeting the minimum loading printed on the label ?
Some monster supplies have a minimum load spec.

I can find very little in the way of specs or a wiring diagram
for the supply. The Tagan web site is a joke. For the
"monster class" power supplies, I recommend getting a wiring
diagram for the wiring harness, so you can understand which
rail of 12V1,12V2,12V3,12V4 is connected where. For the typical
desktop user, a quad is a waste, since one rail is not used
at all.

In this wiring diagram, the 2x4 processor power connector is
supplied from one 12V source.


On this supply, a 2x4 power connector gets half its power from
12V1 and half from 12V2. Those connectors are intended for
a dual socket server type motherboard with two Vcore regulators.


You have to know a fair bit about the supply and the motherboard,
before using the "exotic" stuff.

PS: When a supply like this refuses to work, unplug it (or switch
it off at the back), wait a bit, then switch it back on. If an
automatic protection feature is what shut if off, removing all AC
power will "unlatch" the protection. If it doesn't work at all,
see if the unit has a fuse.

It could be, if you are mixing incompatible technologies
together, that an overcurrent state is being detected by the
supply. In some cases, an improper mix of PSU and motherboard,
can actually burn something on the motherboard, in which case
you'll have more of a mess to clean up. If the motherboard
is fully functional with another supply, then you get to
keep the motherboard.

For example, hold your mouse over the "See Tyan Note" link
in the middle of this page:


It is actually pretty hard to get adequate documentation for
some of these thing. So not all the blame should fall on the


Re: OT Confused over psu

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Thanks Paul - my setup:

Abit AT8-32X ATI RD580 mobo
Watercooled Case
amd 4400 dual core
ati x1900xtx

I tried disconnecting it several times for it not to power up every time -
It does with a spare PSU.
This retry was just with the mobo being powered up - no other components bar

the Abit mobo has one 4 pin (not 6 pin) plug and the standard multi pin - it
also has a 4 pin molex to support crossfire requirements.

I have RMA'd it back and have now got a FSP Sparkle FX700-GLN Epsilon 700W
on route.

From what I can gather one psu for nvidia brds and others for ati

Re: OT Confused over psu

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Depending on the wiring diagram, it could be that the disk drive
connectors are on 12V3, and the motherboard 20/24 pin is on
12V4. Connecting both the Molex for Crossfire and the main
motherboard connector, could cause 12V3 and 12V4 to be connected
together. The PC Power and Cooling monster supplies solve this
problem, by connecting everything not used for the processor,
to 12V3, so there is no chance of a short. There are plenty
of variations from monster to monster.

So the key in this case, could very well have been the Molex
connector on the motherboard surface, causing the problem.
It is not SLI versus Crossfire. For example, there are Asus
SLI motherboards that use the Molex motherboard power connector
concept too, and those boards would not be recommended for
use with a quad power supply (at least, until you check the
wiring diagram).

Sometimes, the solution might be as simple as rewiring some
of the connectors coming from the supply, so that the boost
connector draws 12V from the same supply as the main connector.
I've never done this, or used any of the tools from the
following page, but in theory you should be able to pull
pin and wire, out of the nylon shells of the power supply,
and reorder things as needed. That is, if there are wires
that can be spared for the job.


Maybe you could email Tagan and see if you can get a wiring
diagram. It might give you some idea how clueless they are :-)
There are some power supply rebranders, who know nothing about
the products they sell - those are the really scary ones.


Re: OT Confused over psu

I would return the PSU ASAP. No questions asked.

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