Corsair CX600 Tests Fine

morningster

morningster

morningster

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Yello! Bought a nearly-new Corsair CX600 and tested it with my multimeter (PS-ON shorted to GND) before putting it into my Lenovo Booststation eGPU enclosure (ITX type format).

On testing without load, fan spins up as expected, all voltage rails (on MoBo 24-pin, PCIE 6+2 pin & CPU 8-pin connectors) test fine within ATX tolerances...

When I connect the Corsair CX600 to the eGPU, the fans (PSU fan + enclosure fan) power on but that's all that happens... Checking voltages now, the MoBo 24-pin connector's 12V and 5V supplies are within tolerance but the 3.3V is well under spec at a max of 2.4V! PCIE and CPU voltages all test fine.

The eGPU contains a Sapphire Pulse Radeon RX 6600 XT gfx card with a single 8-pin power connection; fans don't spin up, eGPU is connected to my PC (via Thunderbolt 3) but Windows 11 doesn't detect the card.

This problem does not occur with the original eGPU PSU, a crappy 500W LITEON. Everything works. Only issue is some kind of signal noise on high demand (AAA game title) which causes stuttering in-game (other people have sorted this out using a better PSU).

If there's a bad ripple problem I don't have a scope to check that. I guess the low CPU 3.3V supply is the culprit?

Not an electronics guy so pardon my ignorance: is this likely a simple capacitor replacement issue for the 3.3V rail, a controller issue or something else? Could this be a problem with the SENSE pins?

Might it be worth doing a little DIY or should I just chuck this?

Thanks.


(The seller of the PSU, who seems decent and has a 1000% eBay rating, refunded the sale without my having to send the unit back. I wonder if the unit was damaged in transit.)
 
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Hi and welcome.

Sounds like the psu is faulty (sense wire maybe as voltages all ok) hence your refund, so either get a new one or put your old one back in.


The 6600xt only needs a 500w PSU anyway.

Did you run a game with your old PSU and 6600xt to test ?
 
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Thanks Micky.

So not a straightforward replace / solder jobbie, it seems?

Yes, tried the eGPU mostly to run Elden Ring, which is supposed to be a CPU-intensive game (my laptop has an i5 12500H, also 16GB RAM, should be alright on that front). RX 6600 XT is not a power hungry card, as you imply, but when I get to certain areas in Elden Ring, even just looking around causes stutter and the PSU makes a funny buzzing noise at the same time.

Another person on Reddit had the same problem and resolved it with a new PSU (SFX form factor) but it's a Frankenstein fit so I tried to be clever and get a PSU with the same ATX format and non-standard power socket placement as the eGPU's LITEON; I would only have to remove or internally relocate the Corsair's power button as the LITEON doesn't have one.

Back to the drawing board...
 
It's far more likely the CX600 is fine, but just doesn't like the external enclosure.

Probably if you put a load on the 3.3v rail it'll pull up to something more sensible.
 
leezer3 said:
It's far more likely the CX600 is fine, but just doesn't like the external enclosure.

Probably if you put a load on the 3.3v rail it'll pull up to something more sensible.
Click to expand...
Hello leezer3.

I've never heard of a (sufficicently-rated) PSU being incompatible with a desktop of any kind? Not a PC builder, so what do I know, but seems weird...

Isn't the drop to 2.4V on the 3.3V supply upon load sufficient to prevent operation?
 
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I'm guessing here (not investigated the specific model), but it's more than likely got internal protection circuitry which looks for current draw on the mainboard connector in specific ways.

With the 3.3v, the graphics card won't be using this.
With no load, you'll just get whatever leaks across the transformer circuit. Entirely normal phenomenon, it's just the way the components work.

Basically, it's going to be a lottery as to whether desktop PSUs stuffed into a eGPU enclosure work.
 
It's good you want to try and fix it rather than bin it and buy new, something we should all be trying to do more often.

However when it comes to that, if you are that bothered I'd possibly open it up and spend 5 minutes just visually looking for any obvious signs bulging or discoloured capacitors, otherwise id just let it go and buy a new one.

I don't think it would be worth the time invested otherwise unless you are really bored and fancy it as a project.

If you do spot a bulging cap it could be worth a go trying to solder a new one as they are cheap as chips. Just make sure you jump start it a few times with it disconnected from the mains otherwise you might get a little nip lol.
 
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