Choosing a non 80+ power supply for my rx470

[Noulo]

First of all: No, I can't and won't buy an 80+ power supply (if I understand what a non 80+ plus means), I don't have the money and for what I want it it is not worth it.

 

Hi! I'm going a to buy a very cheap AMD Rx 470 graphics card to repair it. Idk if I will be able to do it but is only 20$, but in order to test it I need to connect it to my also cheap computer. In order to not burn my other pc with it's cheap power supply, I will connect the 470 to a separate PSU out of four I have laying around. The thing is all this PSUs are non 80+, they are just the kind of PSU you would find in a Dell OptiPlex and that kind of office PC (is that what a non 80+ psu is? maybe they are even worse than what I think). They are: one 200w, two 550w and one 450w. Given that the rx470 has a power consumption of 120w, which of these would be less likely to explode if I connect the gpu? the 200w is Dell so I guess that guarantees a liiiiiiittle bit of quality even at 60% efficiency (but it is also really old so idk), I will be posting the photos of all four.

 

Yes, they are old and not what anyone here would want to use, but unless you can guarantee me that they are going to burn my GPU the moment I connect it, help me out deciding what to choose. It is a 20$ purchase, I don't mind too much if something bad happens, and spending 50-60$+ on a proper PSU is not on my capability. Also, I have a friend with a cheap 800w PSU that is considerably newer that I can borrow, but is still not certified, and before I use that one and potentially kill it, I would rather use on of mine.

 

If I can actually repair it I will try to buy a better psu.

 

Is there a way to test them with my tester (multimeter?) beforehand? or any videos to do maintenance to them?

[Spotty]

The "Designed for Pentium 4" should be an indication as to how old those PSUs are, though the sticker on it that says 2005 gives it away.

 

5 minutes ago, Noulo said:

They are: one 200w, two 550w and one 450w.

First it's worth noting that modern systems (made in last 15+ years) will primarily use +12V for power. CPU and graphics card, which consume the most power in a system, both use +12V. Those PSUs are so old they are from an era when PCs used 5V more heavily.

 

The two 550W Delux power supplies can only provide 19A on 12V, 228W

The 450W XTech can also only provide 19A on 12V, 228W.

The 200W Dell PSU can only provide 6A on 12V, 72W

 

None of those power supplies are suitable. They're all eWaste.

[NZKshatriya]

$50-$60 on a proper PSU?

Have you checked PSU prices lately?

 

More like around USD80+

[Noulo]

14 minutes ago, Spotty said:

The "Designed for Pentium 4" should be an indication as to how old those PSUs are, though the sticker on it that says 2005 gives it away.

 

First it's worth noting that modern systems (made in last 15+ years) will primarily use +12V for power. CPU and graphics card, which consume the most power in a system, both use +12V. Those PSUs are so old they are from an era when PCs used 5V more heavily.

 

The two 550W Delux power supplies can only provide 19A on 12V, 228W

The 450W XTech can also only provide 19A on 12V, 228W.

The 200W Dell PSU can only provide 6A on 12V, 72W

 

None of those power supplies are suitable. They're all eWaste.

but isn't 228w enough for the gpu?

[Noulo]

1 minute ago, Caroline said:

Ok that's not how it works, you can't hook up a card alone to one of those relics and expect it to run smoothly. You need to mod some parts of the circuit in order to make it deliver somewhat stable power.

 

The Dell has an output of 6A, that one's not even powering up your xmas lights so you can forget about it, and the rest have 19 which isn't great.

There's a way to do it but before getting into the details I need to know if you're a certified technician and know how to properly handle power supplies and live currents and if you have proper equipment, let's say tools, electronics cleaning products, a strip wired to a circuit breaker and a CO2 fire extinguisher, this last one is just in case.

 

This is something I can do (because I've done it) but I'm not sure I could guide others let alone someone who has never opened a PSU before on how to do it, it's just a bad idea and I won't be responsible for any damage, it's dangerous, and dumb.

well, tools I have and I'm certainly not a proper technician, but my father is an electrician.

[quan289]

As already stated, those power supplies are based on an archaic design when components draw primarily from the 5V  rails, unlike today, where you can have a computer draw primarily on the 12V rail. That's why you see such a high 3.3V and 5V rating, low 12V rating, and the presence of the -5V rail which was removed from ATX specification in 2003/4.

 

You SHOULD NOT used any of those PSUs on a modern day system.

[Spotty]

Just now, Noulo said:

but isn't 228w enough for the gpu?

That's if you actually trust the rating on the label (cheap no-name brands like that often lie on the label to make it seem better than it actually is). Plus it's 15-20 years old so there's a very good chance it either won't turn on, or it'll go bang as soon as you try to use it. Also I'm guessing that power supply was never intended to be loaded up on the 12V rail without a load on the 5V rail, so your voltage regulation is going to be awful on 12V.

 

Looking at the cables in the photo I can't see how any of them would have the 6/8pin PCIe cable used for graphics cards.

Did you have any other PSUs? Do you have a computer that you could borrow the power supply from to test the graphics card?