1 PSU cable to power 3090

[Stahlmann]

Hello good people,

 

tomorrow my 3090 will arrive. I was wondering: My current GPU power cable is a single 8-pin PCIe power cable on the PSU side and it splits up to 2x 6+2-pin cables on the GPU side. The 3090 model i'll have is the Asus TUF with 2x 8-pin connectors. Can i just run this one cable or do i need to run 2 seperate 8-pin cables from my PSU? How do these pigtail-type cables work?

[none77]

Corsair rm650x got 2 pcie cables, 4 connectors.

[Ankerson]

NO, don't even think about it.

 

Your PSU came with 2x PCIe cables.

 

@jonnyGURU

 

 

[APasz]

Not sure I'm understanding the what problem is.

You're going from card with 2x8pin to a card with 2x8pin. Why would you need two cables?

[tkitch]

You really shouldn't try to run 300+ watts through a single 8 pin cable.  You REALLY want both. 

 

 

 

The PSU has two connectors for cables.  Find your second cable.

 

3 minutes ago, APasz said:

Not sure I'm understanding the what problem is.

You're going from card with 2x8pin to a card with 2x8pin. Why would you need two cables?

Pushing too much wattage through too little copper can cause overheating, melting, shorting, and then fire.

It's a bad plan.  The 3090 uses 150+ watts more than the 1080?  Or something like that.  It's NOT a small change in power draw.

[Ankerson]

3 minutes ago, tkitch said:

Pushing too much wattage through too little copper can cause overheating, melting, shorting, and then fire.

It's a bad plan.  The 3090 uses 150+ watts more than the 1080?  Or something like that.  It's NOT a small change in power draw.

 

 

That and he doesn't have enough PSU with 650W in the 1st place, but he will figure that out.

[Fasauceome]

A single 8 pin is rated for 150 watts theoretically, with 2 at 300. add the PCIe slot which delivers 75 watts theoretically. The 3090 is rated for 350 watts by nvidia but can easily pull like 400 or more, as shown in some testing from the likes of Gamers Nexus.

 

So if your combined theoretical output is 375, you're short a good few watts, and you probably don't wanna go over spec on a single cable.

[Moonzy]

are you using the RM650X from your sig?

[APasz]

18 minutes ago, tkitch said:

You really shouldn't try to run 300+ watts through a single 8 pin cable.  You REALLY want both. 

The PSU has two connectors for cables.  Find your second cable.

 

Pushing too much wattage through too little copper can cause overheating, melting, shorting, and then fire.

It's a bad plan.  The 3090 uses 150+ watts more than the 1080?  Or something like that.  It's NOT a small change in power draw.

So you are telling me that every single PSU manufacturer has been breaking electrical safety laws for at least the past 15 odd years?

Just leave the card in it's default state. Cause OCing with only 650w even if it's Corsair is kinda dumb in the first place.

[Guest]

4 minutes ago, APasz said:

So you are telling me that every single PSU manufacturer has been breaking electrical safety laws for at least the past 15 odd years?

That's not what he said.

 

PCIe spec for 8-pin PCIe is 150W each connector.  So two connectors is 300W.  If the card pulls more than 300W, it's the card that's out of spec, not the cable.  That's assuming that no power is being delivered by the slot, of course.  Which should be able to support up to 75W.

 

Theoretically, the cable can deliver more power safely, but you end up with resistance that causes the voltage to drop.  This is why using two cables is ideal.   Less voltage drop.

[Jurrunio]

You can do that, it meets specification of the cables. It's just not ideal.

[Stahlmann]

44 minutes ago, none77 said:

Corsair rm650x got 2 pcie cables, 4 connectors.

43 minutes ago, Ankerson said:

NO, don't even think about it.

Your PSU came with 2x PCIe cables.

I know it came with the extra cables, and i still have them, just asking if i need to use them.

33 minutes ago, Ankerson said:

That and he doesn't have enough PSU with 650W in the 1st place, but he will figure that out.

Had a thread about it yesterday. Most people said it should run, worst thing that could happen is a shutdown when the PSU is overloaded. I'm not planning to OC my CPU and GPU right now. If i have any issues i can still get a better PSU,

27 minutes ago, Moonzy said:

are you using the RM650X from your sig?

Yes. If it is too weak i'll upgrade.

23 minutes ago, APasz said:

Just leave the card in it's default state. Cause OCing with only 650w even if it's Corsair is kinda dumb in the first place.

Not planning to. I know my PSU is at it's limit as soon as i insert the card. I might even upgrade it only because it will probably get loud and hot. I'll see about that as soon as the 3090 is here.

 

 

 

Didn't expect so much input, thanks!

I'll get the 2nd cable and run 2 individual ones. If i have any issues i'll replace my PSU with THIS.

I'll get back to y'all and report if it works or not.

 

EDIT: I didn't expect that 2x 8-pin cables + PCIe slot power are so close to the actual TDP of the card. I hope this will not lead to any issues by itself.

[Moonzy]

4 minutes ago, Stahlmann said:

worst thing that could happen is a shutdown when the PSU is overloaded.

worst *ideal* thing that could happen

[Stahlmann]

3 minutes ago, Moonzy said:

worst *ideal* thing that could happen

Yeah i guess worst thing that could happen is that it will roast my enitre rig. Well, let's see about that...

 

Edit: Shouldn't my PSU have any protection against overloading so the worst thing will not happen? Main reason i want to keep it is because i still have 8 years of warranty, so unless i really have to replace it, i don't want to.

[Ankerson]

21 minutes ago, Stahlmann said:

I'll get the 2nd cable and run 2 individual ones. If i have any issues i'll replace my PSU with THIS.

 

 

That's a downgrade from what you are using now.

 

The RM is not equal to the RMX.

[Stahlmann]

1 minute ago, Ankerson said:

That's a downgrade from what you are using now.

 

The RM is not equal to the RMX.

According to the PSU tier list both the RM and the RMx are in the A-tier. What would you recommend if i had to upgrade?

[Ankerson]

17 minutes ago, Stahlmann said:

Edit: Shouldn't my PSU have any protection against overloading so the worst thing will not happen? Main reason i want to keep it is because i still have 8 years of warranty, so unless i really have to replace it, i don't want to.

 

Yeah, it does, and it should work, but I wouldn't count on it 100%

 

[Ankerson]

3 minutes ago, Stahlmann said:

According to the PSU tier list both the RM and the RMx are in the A-tier. What would you recommend if i had to upgrade?

 

The RMX 850 would be the upgrade from your RMX 650

 

Or the HX 850 or HXI 850 if you wanted to go up another notch in the Corsair lineup.

[Stahlmann]

3 minutes ago, Ankerson said:

The RMX 850 would be the upgrade from your RMX 650

Ok, the RMx 850 W is only ~30€ more expensive than the non x. I guess that's what i'll get if i'll have to upgrade.

[Ankerson]

Just now, Stahlmann said:

Ok, the RMx 850 W is only ~30€ more expensive than the non x. I guess that's what i'll get if i'll have to upgrade.

 

That would be the true upgrade wattage wise and with equal quality.

 

The RM is the budget RM model....

[Jurrunio]

23 minutes ago, Ankerson said:

The RM is not equal to the RMX.

RM is still good tho, isnt it like TX but fully modular?

[Ankerson]

8 minutes ago, Jurrunio said:

RM is still good tho, isnt it like TX but fully modular?

 

No, it's not....

 

http://www.jongerow.com/Corsair_PSU_hierarchy/index.html

 

 

[Mateyyy]

10 minutes ago, Jurrunio said:

RM is still good tho, isnt it like TX but fully modular?

The RM is quieter, fully modular and supports Modern Standby, but it's got no Japanese caps and it's rated at 40C, whereas the TXM is rated at 50C.

So basically, TXM if you don't really care about potential noise, otherwise RM. Or get the best of both worlds (except for Modern Standby) with the RMx.

 

Still though, it's not like there aren't any upgrade options out there other than from Corsair that are similar quality-wise to the RMx (be quiet! SP11, Fractal Design Ion+, you name it). If it doesn't work out with the RM650x OP's already got, that is.

[Stahlmann]

7 minutes ago, Mateyyy said:

The RM is quieter, fully modular and supports Modern Standby, but it's got no Japanese caps and it's rated at 40C, whereas the TXM is rated at 50C.

So basically, TXM if you don't really care about potential noise, otherwise RM. Or get the best of both worlds (except for Modern Standby) with the RMx.

 

Still though, it's not like there aren't any upgrade options out there other than from Corsair that are similar quality-wise to the RMx (be quiet! SP11, Fractal Design Ion+, you name it). If it doesn't work out with the RM650x OP's already got, that is.

https://de.pcpartpicker.com/products/power-supply/#e=6,5,4&A=850000000000,2000000000000&p=1&sort=price&page=1&X=0,20047

 

What would be the best option for an upgrade while not completely breaking the bank? The ION+ actually looks like a great option. Noise is porobably the most important factor for me. I have absolutely no idea what the difference between all these units is, apart form build quality of course. Most of them are in the A tier, so what do i get for the more expensive ones? (I'd probably never buy that GameMax thingy tho, looks scetchy)

[Mateyyy]

5 minutes ago, Stahlmann said:

https://de.pcpartpicker.com/products/power-supply/#e=6,5,4&A=850000000000,2000000000000&p=1&sort=price&page=1&X=0,20047

 

What would be the best option for an upgrade while not completely breaking the bank? The ION+ actually looks like a great option. Noise is porobably the most important factor for me. I have absolutely no idea what the difference between all these units is, apart form build quality of course. Most of them are in the A tier, so what do i get for the more expensive ones? (I'd probably never buy that GameMax thingy tho, looks scetchy)

https://de.pcpartpicker.com/product/MMrcCJ/bitfenix-whisper-m-850w-80-gold-certified-fully-modular-atx-power-supply-bp-wg850umag-7fm

https://de.pcpartpicker.com/product/npGnTW/fractal-design-ion-860-w-80-platinum-certified-fully-modular-at-power-supply-fd-psu-ionp-860p-bk

https://de.pcpartpicker.com/product/dnhKHx/corsair-rmx-2018-850-w-80-gold-certified-fully-modular-atx-power-supply-cp-9020188-na

https://de.pcpartpicker.com/product/CQNgXL/enermax-revolution-df-850-w-80-gold-certified-fully-modular-atx-power-supply-erf850ewt

https://de.pcpartpicker.com/product/VgQG3C/corsair-rmx-2018-850w-80-gold-certified-fully-modular-atx-power-supply-cp-9020180-na

https://de.pcpartpicker.com/product/8z7p99/super-flower-leadex-iii-gold-850-w-80-gold-certified-fully-modular-atx-power-supply-sf-850f14hg

https://de.pcpartpicker.com/product/7cTPxr/be-quiet-straight-power-11-850w-80-gold-certified-fully-modular-atx-power-supply-bn284