5 year old Seasonic Focus Plus 850W Platinum Modular PSU, still good for a 4080 build?

[PaulW]

Hi,
i am specking out a new build after 10 years, with the new build total currently at 3.5k i am looking to save money where i can. sadly the GPU is eating all my budget ( Nvidia). i curently have a 850W Seasonic PSU in my system, at the time i bought (2018) it it was overkill but only £100 then.
my new build on PC partpicker adds up to 635 watts total with a 4080. Can i use my old 850 PSU when everything is on full load? would this be a safe thing to do or should i buy a new 1000W PSU? using my existing PSU would save me £300.

Thanks

Paul

 

[PaulW]

Thank you all for your comments, using this will really help keep the cost down.

 

[PaulW]

What is your full build?

at present its this, subject to change though

Lian Li O11 Air Mini - Black
Ryzen 9 7900X3D
Kingston FURY Beast RGB 64GB (2x32GB) DDR5 PC5-44800C40 5600MHz Dual Channel Kit (KF556C40BBAK2-64)
Gigabyte GeForce RTX 4080 / RTX 4080 founders edition
my existing 850W Seasonic PSU
NZXT Kraken Z63 AIO CPU Water Cooler with LCD Screen - 280mm
Asus ROG Strix B650E-E Gaming WIFI (Socket AM5)
Samsung 990 Pro 2TB M.2 2280 PCI-e 4.0 x4 NVMe 1.3c Solid State Drive

Noctua NF-A12x25 PWM - Black x5 (optional)
Noctua NF-A14 iPPC-2000 x2 (optional)
NZXT RGB & Fan Controller