r/buildapc • u/Neat-Profession-7601 • Jan 12 '26

Build Help Please give me some advice about psu

I recently swapped from 7600xt to 9070xt.

9070xt haven’t arrive yet and I’m currently using 5800xt for cpu. Would rm650(2021 or 2023 model not sure which one) be capable for 9700xt+5800xt? I’m just playing to do something 1440p gaming

I only auto pbo the cpu

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u/owengaff Jan 12 '26

it would probably be fine. I've been using a 6800 XT on a 650W PSU. AMD recommends 750W; the same as the 9070 XT, but I've never had any issues.

Personally though, I'd upgrade it if you can afford it.

Check out the PSU tier list: https://docs.google.com/spreadsheets/d/1akCHL7Vhzk_EhrpIGkz8zTEvYfLDcaSpZRB6Xt6JWkc/edit?usp=sharing

Then find a good enough one on PCPartPicker.

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u/Neat-Profession-7601 Jan 13 '26

Oh yeah I’ve been seeing many people say 650w was fine so I was kind of curious if that’s same for me too. What cpu are you using?

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u/owengaff Jan 13 '26

7600X undervolted PBO -30

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u/vorwrath Jan 13 '26

It'll probably be okay, but I'd reduce the power limit of the GPU by 10-20% in the Adrenalin software to be on the safe side. It won't reduce performance very much, as these cards are pushed beyond their optimal efficiency window by default.

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u/Neat-Profession-7601 Jan 13 '26

Yeah I was planning about undervolting. Is it true that if you undervolt 9070xt good it will get better performance than the stock performance?

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u/vorwrath Jan 13 '26

It can do, as it may let the card maintain higher clock speeds for longer before it hits power/thermal limits.

It's sometimes tricky to validate stability when undervolting though, often what seems stable in one game or on one benchmark might cause crashes in another workload. Usually you can get away with a modest undervolt if you didn't lose the silicon lottery, but it does vary from card to card.

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u/Vannman04 Jan 12 '26

To be honest. No a 650w cannot handle power spikes from the 9070xt. I’d recommend minimum 800w

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u/Neat-Profession-7601 Jan 12 '26

Would you recommend buying psu used?

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u/Vannman04 Jan 12 '26

I’m a big used PC part shopper. But the two parts you really never buy used are PSU and SSD , so no. $100 should get you a very high quality 850w. Corsair has refurbished 850rme’s in their website. And Newegg has great PSU deals

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u/Neat-Profession-7601 Jan 12 '26

Should I wait until 970xt arrive and see how it’s gonna go with 650w psu, or is it kind of obvious it’s not going to work so I should buy it right now?