ATX12VO – MSI MPG Trident AS

15Jan/260

ATX12VO – MSI MPG Trident AS

So this rabbit hole got very deep, very quickly! Bought a new machine... a smaller form-factor unit with great asthetics! Little did I think about any upgrade paths.

It came with an 8gb 4060 Ti which has been flawless for my needs, but I'm thinking I need 16gb... so... as that it's got enough room inside for a better video card? Why not?

I chose an RTX 5070 Ti based on price and RAM. As I was buying the card, the cashier told me I'd need 750+ watts of power and tried to sell me a new supply on-the-spot. Instead, I decided that I'd get home and check what was in the tin first, as brief googlin' indicated that some Tridents came with a Gold Power Supply.

But nope... my MSI Trident contained a 500w SFX. So, I went back to another PC store that afternoon and bought a Cooler Master V850 SFX Gold. A nice amount of power for my card!

Unfortunately, no amount of cable-jiggery-pokery would get the new ATX motherboard power cable to connect to the motherboard power socket? What gives? It turns out the Trident uses an ATX12VO power supply! A short-lived game-over ATX standard that Intel tried to push. They failed so much so that the standard has already been forgotten about. I take it I didn't realise how old this unit was when I bought it. It was a refurb, so it probably lived its life in a gaming cafe.

Trying to find an exact ATX12VO SFX PSU with the correct wattage turned out to be futile. They just don't make them anymore! I started considering re-wiring the old plug from the old supply onto the new PSU, but there's a single pin that doesn't match: +12VSB. This wire is a constant 12v from the power supply to the motherboard for ancillary services. Things like charging USB devices when the machine is off (which could actually cause a lot of current draw?) and the power switch... which, thanks to ATX soft-power, needs a constant current trickle to determine if you've pressed it! I could possible buck-convert the DC, like other people have tried... there's even a project for it here.

The googl' rabbit-hole went deeper and intially I found that Corsair has a custom cable, but I'd already purchased a Cooler Master! I then stumbled across Moddiy's site where they mention Cooler Master and ATX12VO on the same page! They'll create the custom cable for you with inline 12v boost for VSB!

In that last shot it looks like a snake processing a big meal, thanks to the heat sheath.

Cooler Master V850 SFX Pinout

The cable came with no mention of which end was for the PSU. Both ends have the same "ATX plug shape", so I didn't want to plug the damn thing in backwards. IF I had attempted to plug it in, I would've realised that only one side will go into the motherboard, but I was averse to doing it that way.

Instead, I started reversing both ends of both the power-supply-included cable and the new Moddiy cable to work out what was what. Turns out I really only needed to reverse the Cooler Master original cable on the plug, not the socket.

So, looking at the above cable, as it's shown, you get the following pinout:

10P M/B cable (not socket), looking at the plug with the notch facing up...
12v	12v	-12v	+5vsb	POWER_OK
GND	GND	GND	12v	5v

And that means the end of the cable with the 'top-central' pin missing is the Power-Supply side. Everything routed through to the other end, as expected to match the ATX12VO standard.

Of course, the +5VSB didn't, as it goes through the inline DC converter which prevents a continuity test.

Mounting It In The Case

After taking the side panel off the machine, you'll find that the existing power supply has a mains lead running from the rear of the case to it's mounting bracket at the front.

First up you'll want to remove the 4 screws under the machine to release the mounting bracket.

Next, you want to gently push the power supply and bracket up, compressing the cluster of cables above to clear the bottom edge of the case.

Make sure to move any WiFi antennae out of the way! Once it's clear, the power supply can be lifted out via the base, disconnecting all cables (2 motherboard and 1 PCIE) at the same time.

From here, remove the base and attach it to the new power supply. Make sure that the notch is facing right when the power supply fan is facing you. This will allow the fan to line up correctly with the vent on the other side of the case.

Also make sure you switch the bloody thing on if it has an external switch like this one does! There'll be zero access to that once it's installed. Finally, connect the power cable and slide the new supply back into the case.

Line up all the WiFi antennae so you don't pinch them on installation! Route the required power cables to the expected sockets. I actually considered running the SATA power to the drives to take the pressure off the motherboards voltage regulators... but maybe I'll do that later.

Power Test

With it all installed... I just sent it...

A healthy click from the relay inside the new power supply (that's a new feature!) and we're off!

Wooooooooooooooo hoooooooooooo.

New GFX

This is nearly Apple-level packaging. Very schmick!

They also totally overdid the protective film! I suppose they wanted to have ASMR vids from the streamers.

Installation is harmless... just watch out for sharp case edges! Oh, also, the new PCIE 5.1 Power Cable has a right-angle connector housing which is optional: