Powercolor Red Devil Radeon 6800XT - Do I really need an 850 watt power supply for system?

[mannie_freeze]

I stopped by Microcenter in St. Davids, PA (outside of Philly) and they had some Radeon 6000 series GPU's in stock surprisingly. On a whim, I picked up the Powercolor Red Devil 6800XT since I don't know whenever I will get my hands on one of the 6000 series GPUs in the near future. According to Powercolor, it recommends using an 850 watt power supply. Do I necessarily need this kind of power supply?

 

The reason why is I am planning a build with a Lian Li O11 Dynamic Mini which can only support an SFX/SFX-L power supply. I know anything above 750 watts in SFX/SFX-L format is not common. After checking multiple watt calculators, a lot them said I would be fine running a 650 or 750 watt power supply. Since this is my first "expensive, balls-to-the-wall" build I'm hesitant to run 100-200 watts below recommended. I will provide planned build parts at the bottom of post.

 

I was looking at the Silverstone SX800-LTI power supply that Linus used in the "I Built an All AMD Mini PC!" video posted on 21Dec2020: https://youtu.be/R4jTCGkuXyg 

 

Should this be enough power even though it is 50 watts below recommended? I also saw Silverstone released a 1000 watt SFX-L power supply, SX1000 Platinum, but according to their reps on the company's website the restock probably will not happen until mid-late January. I also see Cooler Master has an 850 SFX power supply but I do not see any in stock or see any positive reviews about it. If anyone actually has positive reviews of the Cooler Master power supply then please chime in.

 

To recap, my question is do I really need an 850 watt power supply for my system? Should I be fine running with a Silverstone SX800-LTI? Should I wait for the Silverstone SX1000 Platinum? Is the Cooler Master 850 SFX good and should I consider it?

 

For my planned build, the goal for my build is "small" with power and complete RGB. My planned build is as follows:

• Chassis - Lian Li O11 Dynamic Mini (Black) - On preorder, will arrive sometime in mid-January
• CPU - AMD Ryzen 7 3800XT
• Motherboad - MSI B550M Mortar (microATX)
• GPU - Powercolor Red Devil Radeon 6800XT (unplanned)
• Memory - Trident Z Neo 32GB (2 x 16GB)
• AIO Cooler - NZXT Kraken Z73
• Fans - Lian Li UNI Fan SL120 up to 10 (only can get my hands on a couple for now, will add the remaining later)
• Power Supply - ??????????????????????????

[Prodigy_Smit]

With your CPU the 750w would be fine. They generally run those tests with a maxed out CPU to eliminate bottlenecks like a Ryzen 9 5900x or a 10900k.

[Analog]

650W probably will be fine, but it will be borderline, meaning it won't really give you any real headroom for future upgrades. Better go with a 750W unit if you can find one. 

[G0dSpeed]

750W would be fine 650W would be really pushing it.

[RejZoR]

Given I'm running my RTX 3080 on 750W PSU (though it is a high end one) and it's fine, these Radeons consuming a bit less should be just fine.

[mannie_freeze]

Thank you @Prodigy_Smit, @Analog, @G0dSpeed, and @RejZoR for your input! I appreciate it very much!

 

I feel confident now going with a 750 watt power supply or the Silverstone SX800-LTI if I can find it in stock.

[Sav9]

my x570 can pull 300 OC I snagged a devil that pulls over 300 at times its bad to run your psu at 80-90 percent load itll get hot rule of thumb trying keep your power draw at 3/4 your total watts, keeps things running cooler. Just my personal opinion

 

[Bobbysixjp]

Congrats on the GPU - I’ve had mine with a few weeks now and very happy with it. I have a Corsair 850 W PSU. 

[gloop]

3 hours ago, Sav9 said:

its bad to run your psu at 80-90 percent load itll get hot rule of thumb trying keep your power draw at 3/4 your total watts, keeps things running cooler.

Source?

[airborne spoon]

1 hour ago, gloop said:

Source?

from the corsair website:

Typically, your power supply's maximum efficiency is between 40% and 60% of it's maximum capability.

here is a graph of a 750W PSU and you can see it is most efficient right around 50%, and most other PSU have a very similar curve to them.