Do you know what the best combination of low cost + reliability would be when it comes to PSUs?
So, this is definitely in my wheelhouse, as another of the moderators here likes to say. Unfortunately though, there is no such thing. There are exactly ZERO "low cost but reliable" power supplies. ESPECIALLY right now, or pretty much, since about the time that the pandemic plus the giant cargo freighter that got stuck in the Suez canal happened and completely screwed up the supply chain for probably years.
In light of that however, regardless of which way you go on the graphics card, since quality units under 550w tend to be just as expensive, or more, than those with higher capacities (Because higher capacity units with any quality at all tend to sell in much larger numbers than lower capacity models), this is probably the very best, least expensive option out there right now. It's a somewhat older model/design/platform, but one that was very good and well recommended just a few years back and would be more than suitable for this type of build assuming fitment, which also severely limits the options as the majority of quality power supplies that are less expensive, also tend to be longer than the 140mm you suggested as the maximum length able to be used in this case. This unit is 750w, which is perfectly fine, and is the same price as the exact same model in a 650w unit, so doesn't make sense to not get the 750w model as the platform is reliable but is known to be noisy under heavy load. The fact that it's reasonably higher capacity than any of the hardware you are planning to use, would ever need, means it would pretty much be noise free operation for it's lifetime which would likely extend that lifetime somewhat as well.
There are definitely less expensive models out there, but honestly, there are none that will fit, that are less expensive than this unit right now, that I would trust. And if there are no professional reviews of a unit, or at least of some other unit using the same platform, I will not use or recommend others to use it.
PCPartPicker Part List
Power Supply: Corsair CX750M (2021) 750 W 80+ Bronze Certified Semi-modular ATX Power Supply ($79.98 @ Amazon)
Total: $79.98
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2023-11-08 14:29 EST-0500
Aris, who is arguably about the most knowledgeable PSU reviewer and engineer in the world, with maybe only Jon Gerow (JonnyGuru) coming in at a close second, says the platform is reliable.
The Corsair CX-M Series 650 W is one best available budget PSUs. It performed very well in our tests and runs reasonably quiet. Given the affordable positioning it shouldn't be an issue that it lacks the 12+4 pin PCIe connector for future GPUs, most budget PSUs won't meet the strict ATX 3.0...
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