Dual SFX PSUs

[DKims]

To preface, the plan for the build is a 5950x and a 3090, with the 5950x and ram overclocked and the 3090 at factory OC. The case is most likely going to be a Lian-Li O11D Mini.

 

Which brings me to the title. The O11D Mini only takes SFX/L PSUs and the only 1000w I can find is the Silverstone SX1000 which also has a stupid price hike right now (and cablemod doesn't support it - I don't mind making custom cables but if I can avoid the hassle I will). Then I found out the case can take two SFX PSUs so the new plan was to buy two 600w (or whatever wattage, 600 just seemed like a more than adequate number) SFX PSUs and power the 3090 off the second one. So now the question is, is it fine to just use a 24 pin ATX splitter and power the 3090 from the second PSU's PCIe connectors, or would I need something else since the GPU is also powered by the PCIe slot on the motherboard (effectively being powered by both PSUs I guess, which seems like something I should avoid after a bit of research)? Also would just having the splitter shut down both PSUs or would I need to manually shut down the second one?

 

[jaslion]

Why not get a different case? The o11 mini is the size of a regular mid tower case anyway.

Dual psu's work but are NOT recommended especially with a system like this.

[Freakwise]

16 minutes ago, DKims said:

is it fine to just use a 24 pin ATX splitter

Something like this?

 

Technically it was fine since it was only used to trigger the psu into "on" state but like @jaslion said dual psu is going to work but not recommended, especially for system like this

 

[bellabichon]

I think you're overestimating how many watts you'll need for this build. The 3090 and 5950X are definitely power-hungry, but a decent quality 850W SFX/L unit should do you just fine. 

[DKims]

8 minutes ago, jaslion said:

Why not get a different case? The o11 mini is the size of a regular mid tower case anyway.

Dual psu's work but are NOT recommended especially with a system like this.

Was kinda set on it just because I like how it looks a bit better than the regular one. I don't mind having to switch cases if it isn't feasible. That being said, why isn't it recommended in this system specifically? I don't see how this is really any different from other dual PSU setups.

[DKims]

2 minutes ago, bellabichon said:

I think you're overestimating how many watts you'll need for this build. The 3090 and 5950X are definitely power-hungry, but a decent quality 850W SFX/L unit should do you just fine. 

I thought that too, especially at stock, but people have reported OCP tripping on certain PSUs (with their components overclocked) and I wasn't willing to really dig down the rabbit hole to see which models/revisions made their OCP less sensitive. I also plan to custom loop with quite a few RGB fans so I wanted to leave some headroom in case the GPU has a power spike during workloads (ie. When switching scenes or when starting trainings on new dataset batches). I could also just turn off the RGB when doing this and I'll probably just get annoyed by them after a while anyway, but juuust in case lol.

[jaslion]

2 minutes ago, DKims said:

Was kinda set on it just because I like how it looks a bit better than the regular one. I don't mind having to switch cases if it isn't feasible. That being said, why isn't it recommended in this system specifically? I don't see how this is really any different from other dual PSU setups.

The main issue is for devices that pull from both psu's. If they have a voltage mismatch which can easily happen when the secondary psu is only powering the gpu and thus running at such low amperage that the voltage can drop below 12V. This can trigger a protection on either unit as the gpu is getting 12V from the pcie slot but 11.4V from the pcie connectors and thus triggers protections and a shutdown. It is a lot less common and people that mine dont have the issue but regular desktop users can still run into it without doing much.

 

I would just recommend a different case or if your really want the o11 the regular one. That or a 850w high end sfx psu.

[jaslion]

5 minutes ago, DKims said:

I thought that too, especially at stock, but people have reported OCP tripping on certain PSUs (with their components overclocked) and I wasn't willing to really dig down the rabbit hole to see which models/revisions made their OCP less sensitive. I also plan to custom loop with quite a few RGB fans so I wanted to leave some headroom in case the GPU has a power spike during workloads (ie. When switching scenes or when starting trainings on new dataset batches). I could also just turn off the RGB when doing this and I'll probably just get annoyed by them after a while anyway, but juuust in case lol.

Ok yeah then a 850w unit would be pushing your luck a little.

[BetteBalterZen]

44 minutes ago, bellabichon said:

I think you're overestimating how many watts you'll need for this build. The 3090 and 5950X are definitely power-hungry, but a decent quality 850W SFX/L unit should do you just fine. 

True, because if OP won't touch powerslider on the 3090, I'm pretty sure all 3090's are capped at 350w.