What PSU to get?

[FiizZniiTz]

Hi, so I'm new to the PC world and looking to build my first PC. I have all of my parts selected apart from the PSU. i was thinking of getting the Corsair Rmx (2018) 850W but not sure if there is something better for a similar price?
Not sure if this info is needed but I am going to be getting a ryzen 5600x and either the 3080 or 6800XT

[CPGP]

This Gamers Nexus video should equip you well for deciding what size of PSU to get:
https://youtu.be/X_wtoCBahhM

In most systems, the CPU and the GPU are going to dictate most of the power usage. The rest of the components (motherboard, disks, RAM) will also consume some power too.

In your case, the 5600X is ~65W. The 3080 is ~320W. The 6800XT is ~300W. So the CPU and GPU require about ~400W.

We also need to add the other components. I'd ballpark it and add about 200W, unless you're planning to hook up a lot of HDDs (~15-20W each when spinning up!). This is quite generous, but it is considered unhealthy to run the PSU at 100% load all the time, so this also gives it some buffer. That gives us about 600W total.

Curiously enough, the full specs on the Nvidia 3080 site say that total system power (e.g. PSU) should be 750W. I'm not sure what they base this off, considering this is only the GPU and Nvidia wouldn't know about any of the other components. I suspect this is just a wild (and fairly safe) guess on their part.

If you've already decided on most of the parts of the system, if you add all of those parts to the system builder on PCPartPicker, it'll give you an estimate on the wattage required. Do note that it may not know all the parts' wattages, so be sure to watch the video above and make a call.

Once you've decided the wattage, it is then a case of choosing the efficiency/price/brand you like. Once again, the video above can tell you how much each matters.

[Matt72933]

Check this calculator out

https://outervision.com/power-supply-calculator

850w should be fine, and I've never had any issues with Corsair PSU's, on my 3rd now, not through failure, just additional machines. I've been using the HXi range. 2x 750w and 1x 1200w absolutely silent operation.

[virtuo]

I think the Nvidia estimates assume a fairly low efficiency unit and probably overquoted to cover their backs. I've found the stock of 750W and above gold/platinum units to be evaporating quickly. Tried to get a Seasonic but ended up with a Corsair HX850 (non-i) platinum unit. A little old now, but still reviews very well.

I've had a Corsair RM before, which I understand to be their budget line, and the fan bearing has gone in it, making it particularly noisy. But other than that it still works.

[Xlucine]

I think the Nvidia estimates assume a fairly low efficiency unit and probably overquoted to cover their backs. I've found the stock of 750W and above gold/platinum units to be evaporating quickly. Tried to get a Seasonic but ended up with a Corsair HX850 (non-i) platinum unit. A little old now, but still reviews very well.

I've had a Corsair RM before, which I understand to be their budget line, and the fan bearing has gone in it, making it particularly noisy. But other than that it still works.

Efficiency doesn't come in to it, as the rated capacity of a PSU is the output. It's partly covering their backs, and partly to cover the poor design of the 3000 series cards (with transient spikes well above TDP that are enough to trip the overcurrent protection of any PSU that isn't massive overkill for the average power needs)

[FiizZniiTz]

Thank you guys for all your help! After looking into the resources provided it seems like 650W should be enough, however I will go for 750W just to ensure it is never at full load.

[XD_3VIL_M0NKEY]

Thank you guys for all your help! After looking into the resources provided it seems like 650W should be enough, however I will go for 750W just to ensure it is never at full load.

Biggest bit of advice - don't scrimp on your PSU - it's the lifeblood of your PC. Invest properly!
A £50 800W PSU is a guaranteed timebomb vs a £150 800W PSU.

[iiTsMus]

I'd recommend a Bitfenix Whisper M 650 or 850

[beebub]

Just one further thing to consider. Do you _need_ it to be modular? How important is cable management to you? Corsair for instance has about 6 different 850W PSUs and aside from the efficiency ratings, you have to choose between modular, semi-modular or non-modular. If you can just tuck the excess cables away (as I did) you can save yourself a bit of money. The only cables visible in the main viewable area are the ones run to components - the rest are hidden behind the back or in the void underneath on the same level as the PSU in my P400A case. Just my 2p.

[rich_27]

I had the same question but thought I'd comment here instead of starting a new post - I hope that's alright. I have the following system (see end of post), and I'm not sure whether I've overspecced the power supply or not; PC Part Picker estimates the wattage at a little over 350W, though that isn't including the pump of the Asetak 645LT (not in their database).

What I was wondering is I've read that you want to be targeting about 50% load on your power supply at average power draw to hit the sweet spot on the efficiency curve, however - as far as I'm aware - the average power draw of your components is usually significantly lower than their rated power consumption, tdp, or peak power. What kind of a wattage margin do you want to add for safety, and how do you figure out how to nail the sweet spot of the efficiency curve for a given power supply?

I know we are talking efficiency gains of a few percent at best, yet I have a compulsion to do it right Looking at a calculator like overview, it recommends a 80+ bronze 450W power supply, which feels quite low and quite inefficient - efficiency matters quite a bit to me, because any inefficiency is excess heat dissipated into my case, and it's already going to be a tight squeeze component-wise and thermally in the Dan A4!

Type	Item	Price
CPU	AMD Ryzen 5 5600X 3.7 GHz 6-Core Processor	Purchased For £299.99
CPU Cooler	Asetek 645LT 92mm SFF AIO Liquid Cooler	Purchased For £76.34
Motherboard	MSI MPG B550I GAMING EDGE WIFI Mini ITX AM4 Motherboard	Purchased For £149.99
Memory	Corsair Vengeance LPX 16 GB (2 x 8 GB) DDR4-3600 CL16 Memory	Purchased For £79.99
Storage	Samsung 980 Pro 250 GB M.2-2280 NVME Solid State Drive	Purchased For £84.98
Storage	Samsung 860 Evo 1 TB 2.5" Solid State Drive	Existing Component
Video Card	Gigabyte GeForce RTX 3070 8 GB EAGLE OC Video Card?	£672.95 @ Overclockers.co.uk
Case	DAN Cases A4-SFXv4.1 Mini ITX Desktop Case	Purchased For £195.44
Power Supply	Corsair SF 600 W 80+ Platinum Certified Fully Modular SFX Power Supply?	£119.87 @ More Computers
Monitor	LG 27GL83A-B 27.0" 2560x1440 144 Hz Monitor	Purchased For £178.00
Monitor	LG 27GL83A-B 27.0" 2560x1440 144 Hz Monitor	Purchased For £178.00
Keyboard	Dell KB212-B Wired Standard Keyboard	Existing Component
Mouse	Logitech MX Ergo Wireless Optical Mouse	Existing Component
Speakers	Logitech Z200 0 nW 2.0 Channel Speakers	Existing Component

[Sam 359]

850w and anything with a 10yr warranty, seasonic are great