Question Is my HX850i enough for RTX4090?

[kimccino]

Hello,

I currently have:
Z390 Aorus Pro,
i9 9900k, planning to overclock in the near future,
64GB RAM
PSU is Corsair HX850i Platinum,

HX850i only has 3 x 8pins, so I am going to plug three cables to the GPU, probably maxed out at 450~525w but I was planning to reduce the power target of the 4090 anyway.

The big question here is if 850w was enough for the 9900k to overclock.

 

[Aeacus]

The big question here is if 850w was enough for the 9900k to overclock.

While running RTX 4090 as well? No.

CPU alone, can draw 200-250W from OC,
review: https://www.tomshardware.com/reviews/intel-core-i9-9900k-9th-gen-cpu,5847-11.html

So, if you add things together; 250W CPU + 450/525W GPU = 700/775W for two components alone. Add the rest of the system at ~150W and you'll blow your PSU.

Even without CPU, CPU OC or the rest of the system, RTX 4090 transient power spikes alone, can blow your PSU.

View: https://www.youtube.com/watch?v=wnRyyCsuHFQ


For RTX 4090 and due to the extreme power hungriness, 1.2 kW PSU would be what i'd consider, preferably 1.5/1.6 kW PSU.

When you have 1.5-2 grand to fork out for RTX 4090, you'll also have money to buy proper PSU, e.g Corsair AX1600i.

 

[Fix_that_Glitch]

The 4090 does not respond well to under volting. And why would you spend all that money on a gpu and reduce it's potential? (I have purchased a 4090, still tapping my fingers waiting on delivery.) I bought an Msi Atx 3.0 Pcie 5 1000w for mine as I do not want to take any chances when I pair it with the 13900k. With a 9900k you are looking at 200w+ power draw overclocked and add in 300-320w power draw from gpu, you are at around 520 watts, throw in motherboard and near 600w steady power draw not possible spikes. The spikes are what everyone is running around trying to scare everyone. Efficiency is what I am concerned about. No one is talking about that. So that is why I purchased a 1000w psu. Your 850w platinum will be able to handle your build.

 

[kimccino]

While running RTX 4090 as well? No.

CPU alone, can draw 200-250W from OC,
review: https://www.tomshardware.com/reviews/intel-core-i9-9900k-9th-gen-cpu,5847-11.html

So, if you add things together; 250W CPU + 450/525W GPU = 700/775W for two components alone. Add the rest of the system at ~150W and you'll blow your PSU.

Even without CPU, CPU OC or the rest of the system, RTX 4090 transient power spikes alone, can blow your PSU.

View: https://www.youtube.com/watch?v=wnRyyCsuHFQ


For RTX 4090 and due to the extreme power hungriness, 1.2 kW PSU would be what i'd consider, preferably 1.5/1.6 kW PSU.

When you have 1.5-2 grand to fork out for RTX 4090, you'll also have money to buy proper PSU, e.g Corsair AX1600i.

Appreciate your feedback, that's a good point, I think I will go without CPU OC, until I get a new PSU, thanks for the GN vid, I will check it out.

The 4090 does not respond well to under volting. And why would you spend all that money on a gpu and reduce it's potential? (I have purchased a 4090, still tapping my fingers waiting on delivery.) I bought an Msi Atx 3.0 Pcie 5 1000w for mine as I do not want to take any chances when I pair it with the 13900k. With a 9900k you are looking at 200w+ power draw overclocked and add in 300-320w power draw from gpu, you are at around 520 watts, throw in motherboard and near 600w steady power draw not possible spikes. The spikes are what everyone is running around trying to scare everyone. Efficiency is what I am concerned about. No one is talking about that. So that is why I purchased a 1000w psu. Your 850w platinum will be able to handle your build.

Thanks heaps, I think I will eventually invest in 1200~1500w PSU, but initially just go without CPU OC and see how the next gen PSUs are shaping up,