[SOLVED] Upgrading GPU on a junk PSU

[alex.mihai310]

Hello.
My friend recently told me he wants to upgrade his old hd 7790 and i found a pretty sweet deal on an used RX580. Thing is, he can't afford buying a new PSU too right now.
My question is, if he does buy the RX580, would decreasing the power limit let him use the card ( at lower performance, of course ) until he can buy an adequate psu?

 

[PC Tailor]

would decreasing the power limit let him use the card

The problem is not about the amount of power something is using. The problem is the way that a junk PSU can be much more unpredictable. How well does it regulate the power? How well does it deal with noise / ripple? What happens in a surge or a brownout?

The problem with junk PSUs is not power, it's quality.

I've had people buy a junk PSU 2 to 3 times the recommended power requirement of the GPU, and it has still blown and taken out their brand new GPU.

So can they use a junk PSU with it? Yes.
Is it a good / safe Idea? Not really.

 

[alex.mihai310]

Thanks for the fast reply .
Some time ago he upgraded his old cpu with an i5 3rd gen, i don't know the exact model, but I know that the TDP was 65w, because I also had trust issues with that PSU. I ran synthetic loads on both the CPU and GPU at the same time for approx. 30 mins, and it seemed to be okay (intel burn test and furmark for reference). The 7790 has a factory TDP of 85w, but his version is also OC'd, so I thought it would handle lowered power draw from the RX. I'll still bug him to not use it until he gets a new PSU, but there's not really much I can do there .

 

[PC Tailor]

TDP was 65w

Remember that TDP is not necessarily the same as power usage. TDP is thermal design power and is only power disappated as heat, not overall power usage. Your power usage can actually go far above or below this depending on your system setup, The TDP is the maximum power that one should be designing the system for.

I ran synthetic loads on both the CPU and GPU at the same time for approx. 30 mins, and it seemed to be okay

The problem with this again is just because a PSU doesn't go pop in one instance, doesn't mean it won't in the next. The problem with junk PSUs is they are unpredictable. I've had junk PSUs pop and give off smoke in 5 minutes of use, and also some after 5 years of use.

 

[alex.mihai310]

That makes sense. Then, can you give me some recommendations on a budget PSU?
edit: What I could find was a gigabyte p450b at about 40$.

 

[PC Tailor]

Gigabyte aren't exactly renowned for their quality. "Budget" can often spell danger, it's the same as buying a $800 Camera and then paying $2 for the flimsiest case to carry it in, yes it will probably function - but it's cheap for a reason, and then what will happen to the camera if you drop it?

You also want a tiny bit more than 450W just in case for a 580. As AMD recommend 500W and some tests i have seen also seem to suggest 500W is sensible.

But assuming you are referring to USD (I'm not USA), based on current prices I would actually recommend this as it's a decent unit that's currently low price:

Power Supply: Antec NeoECO Gold ZEN 500 W 80+ Gold Certified ATX Power Supply ($69.99 @ Newegg) - Total: $69.99

Worst case you could maybe push this but it's not as good as above and is a lower quality unit:

Power Supply: EVGA BQ 500 W 80+ Bronze Certified Semi-modular ATX Power Supply ($62.89 @ Amazon) - Total: $62.89

Usually the minimum I would recommend is this, but the NeoEco Gold Zen above is actually great value IMO (and from my awareness, as I said, not US based):

Power Supply: Corsair CX (2017) 550 W 80+ Bronze Certified ATX Power Supply ($74.98 @ Amazon) - Total: $74.98

You can also shop around to find cheaper ones and obviously let me know and we can see if you find any decent enough units. It's worth noting as well these are above that $40 units, but these are not "excellent" units above, I am purposelly picking budget friendly ones that are adequate for the setup you described.

 

[alex.mihai310]

I'll take some time to search around the market. As far as I know, I should look for antec/sirtec/seasonic/evga/corsair most of the time.
And as you did answer my first question, and I am very thankful for that, I'll mark this topic as solved. Again, many thanks! Have a great day.

 

[PC Tailor]

As far as I know, I should look for antec/sirtec/seasonic/evga/corsair most of the time

Not necessarily. This is just an information - brand is irrelevant. Because practically every brand makes good units, AND also bad ones. (Also Sirtec are a manufacturer and aren't a brand of PSU you would buy, they make PSUs for Brands to put their sticker on effectively - at least not from any part of the world I know of).

So for example, EVGA are typical of this, they have a TON of trash units, N1, W1, B, etc. But they also have some good units, like the SuperNOVA series (generally).
Corsair have great units, but also have the VS, which is made for much lower spec machines.
Seasonic have great units, but also have the S12 and M12 which whilst good for their time, are dated platforms.

I would just say that overall, choosing brands like Seasonic and Corsair, you are much less likely to pick a bad unit as their line are more good than anything else.

So it's the specific model you want to look at, just because it is branded, does not mean it is good.

Just for information in case you see a really cheap EVGA unit and end up buying it thinking it must be better as it's EVGA!

You're welcome my friend, just let me know if there is anything else!