Showing results for 
Search instead for 
Did you mean: 


Journeyman III

Question about psu

Hello people, 

my question is pretty simple. I’m swapping to a Ryzen 9 5900x, I have a b550 as motherboard and a 3070 as gpu. Is my 750w psu enough to power this pc up? 


10 Replies

According to Nvidia your RTX 3070 requires a Minimum PSU of 750 Watts so with your Ryzen 9 5900X should be enough for your PC under regular loads.

This website that recommends PSU for GPU/CPU combo hardware, in my opinion, which under powers the PSU minimum requirement but you can see for yourself:

Screenshot 2024-01-18 132423.png

The above link indicates you only need a 550 watt PSU minimum to run your set up.

I believe they are talking about actual power use but the reason why PSU Minimum Requirements are so much higher than the GPU's actual power usage is due to GPU Power spikes that can spike high enough to crash your PC due to the PSU not having enough power to compensate for the power spike.

I read this a couple of years ago in a Asian Engineering report, don't know how reliable it was, about why PSU should have a higher minimum power requirement due to GPU power spikes.

NOTE: But if you ever decide to upgrade your PSU try to buy one, at least, 1000 watts or higher to future proof your PC for power usage when you decide to upgrade your PC hardware again.

Thanks a lot for the detailed reply!

i checked those sites and stata before coming here to write the question exactly because those low psu made no sense to me ahha. I’ll try to go with 750w and if it causes problems I’ll go with 1000

If you haven't purchased yet the 750 watt PSU then I suggest you go for at least the 850 Watt PSU.


Big Boss

ImGenemy, I suggest 1000W with that power hungry GPU and a good quality processor cooler. Enjoy, John.


Nobody asked you what power supply you have.

Not all power supplies are made equal, and that's why you have this prevalent over-estimation of wattage needed. If a manufacturer says you need a 500W power supply and you go buy a $20 piece of crap and it fries your system then they're at fault cause they said it would work, right?

A 3070 draws 220W, or 250W if it's an OC model. You can't go by CPU TDP - look at reviews. A 5900X draws 135W stock all-core max, it can go much higher if overclocked, but even that 200W would be the max. So we're talking about a power draw of the 2 primary power-hungry components of around 350W or maybe up to around 450W if overclocked.

If you have a DECENT 80-Plus power supply rated at 750W then that is MORE than sufficient to power that system, even overclocked.

Ryzen R7 5700X | B550 Gaming X | 2x16GB G.Skill 3600 | Radeon RX 7900XT

The CPU TDP is a rating to select the proper CPU Cooler. As you mentioned the processor can consume much more wattage than its TDP rating.

I also agree that a HQ Metal Rated 750 Watt PSU would be sufficient for his hardware in his PC. But the price difference between a 750 and 850 Watt PSU is not that great. Which is why I recommended he gets at least a 850 Watt PSU to have some leeway in case he decides to upgrade his GPU again.

True about PSU not all being the same depending on the quality of the PSU is one reason for over-estimating the PSU wattage but another reason is that GPUs generate some high power spikes that can easily exceed the PSU wattage. The over estimation of PSU wattage takes this into account.

In the past I was also wondering why the PSU Wattage minimum requirement was so much higher than the actual power draw of the GPU until I read a Asian Engineer's report about GPUs generating for milliseconds high power usage or spikes.

Found this website that explains what I am talking about showing Power Spikes for both Nvidia and AMD GPUs:

Screenshot 2024-01-18 181948.png

Screenshot 2024-01-18 182120.png

Agreed there are variables, too many to blanket statement based solely on wattage rating of the PSU. I took the OP as stating he already HAD a 750W power supply and was asking if that was sufficient. Definitely need more info on make/model before can be determined solid yes/no. Although a 750W rating is kinda high for a cheap OEM but suppose it's possible.

Ryzen R7 5700X | B550 Gaming X | 2x16GB G.Skill 3600 | Radeon RX 7900XT

I also understood that the OP already had a 750 Watt PSU and was asking if it was powerful enough for his PC.

But his second reply seemed to indicate that he is thinking about purchasing a 750 Watt PSU which is why he opened this thread.


You should be totally fine, i have 7900X with 6800 XT and my PSU is 750 watts platinum. As @elstaci said, the total of your system under 100% workload will not be over 400 watts, so you should be fine dont forget to undervolt your both CPU and GPU so you get more performance at lower wattage and temperatures, and also prolong their lifespan. Best of luck.    

Journeyman III

Thanks for answering, it helps me a lot. You made my day.