850 Watts 2nd hand vs 1000 watts new - help with building a new system

[John.Isr]

I'm currently building a new sfx system with a 7800X3D and a 4090.

On PCPartPicket it says that my estimated power consumption will be ~720 Watts

I need to decide between a 2nd hand white Lian-Li SP850, vs a corsair SF1000Lthe former is basically a 10th the cost of the latter in my country...

Any advice?

[i like xeons]

Please don't buy a used power supply

[MiszS]

7 minutes ago, i like xeons said:

Please don't buy a used power supply

why? those are perfectly fine, unless you buy a shitty power supply, it isn't going to explode. As for the question, 850W should be fine, but that's pushing the limits, if you can afford a 4090 it's a good idea to get a 1000W psu, but if the price difference is 10 times, then i'd chose 850W

[i like xeons]

Personally i would not buy a used PSU unless there is no other option but sure, u can if u want
Also consider PSU degradation

[MiszS]

1 minute ago, i like xeons said:

Personally i would not buy a used PSU unless there is no other option but sure, u can if u want
Also consider PSU degradation

It does exist, but it's not that big of a problem, depends on how it was used obv, if it was pushed to the limits the entire time, then yeah it would probably degrade

[GuiltySpark_]

I never buy used PSU's, just a good one and use it for many years. 7800x3D / 4090 can run comfortably on a quality 750W so don't go overboard if you don't have to. You absolutely do not need a 1000W PSU. Buy what you can get new, if you're buying a 4090 a budgeting for a PSU is a concern, you have some budget issues you need to work out. 

[John.Isr]

Considering the difference in cost, shouldn't I buy the 850Watt one, and if I experience crashes or anything just replace it, am I missing anything?

Am I risking anything by not buying the 1000Watt PSU?

Is there any serious chance of a Lian-Li PSU exploding or catching on fire because I tried to draw more power than it can provide?

@MiszS

@i like xeons

[John.Isr]

2 minutes ago, GuiltySpark_ said:

 Buy what you can get new, if you're buying a 4090 a budgeting for a PSU is a concern, you have some budget issues you need to work out. 

I got a HUGE discount on my 4090, if I hadn't I wouldn't have gotten it. A full price one is way out of my budget.

[-rascal-]

5 minutes ago, John.Isr said:

Considering the difference in cost, shouldn't I buy the 850Watt one, and if I experience crashes or anything just replace it, am I missing anything?

Am I risking anything by not buying the 1000Watt PSU?

Is there any serious chance of a Lian-Li PSU exploding or catching on fire because I tried to draw more power than it can provide?

@MiszS

@i like xeons

 

No, if you don't buy a "Fuyao Factory" PSU, it should have the STANDARD safety features built into it...over-current protection, over-voltage protection, etc.

If you draw more power than what the PSU can output, the PSU should shut down, not explode.

 

A quality 850W should be more than enough, not necessary to get such as high wattage.

[GuiltySpark_]

10 minutes ago, John.Isr said:

and if I experience crashes or anything just replace it,

Why is this a concern? I've been playing a lot of a 7800x3D and 4090 for near a year now and the most my UPS says I'm ever pulling from the wall is 550W, maybe. Stock 450W power limit on the 4090. 

 

Card is so unbelievably fast there is no reason to change anything.

[MiszS]

11 minutes ago, John.Isr said:

Considering the difference in cost, shouldn't I buy the 850Watt one, and if I experience crashes or anything just replace it, am I missing anything?

Am I risking anything by not buying the 1000Watt PSU?

Is there any serious chance of a Lian-Li PSU exploding or catching on fire because I tried to draw more power than it can provide?

@MiszS

@i like xeons

Nah, the psu is a quality one, so nothing bad should happen even if you did exceed the power limit, but that would be pretty hard to do with your current setup, so you should be fine

[i like xeons]

9 hours ago, John.Isr said:

Considering the difference in cost, shouldn't I buy the 850Watt one, and if I experience crashes or anything just replace it, am I missing anything?

Am I risking anything by not buying the 1000Watt PSU?

Is there any serious chance of a Lian-Li PSU exploding or catching on fire because I tried to draw more power than it can provide?

@MiszS

@i like xeons

I think the only thing you are missing out on is some reliability and futureproofness