PSU Help, first time build

[Blake404Frye]

Hello all, this is my first every post on this forum (which I have received much information from prior to) and I am in need of some clarity when it comes to PSUs.

I am getting a lot of mixed readings regarding whether or not 550w SeaSonic G series PSU will be able to comfortably power my build I am about to take on.

The Build is as follows:

• MSI GTX 1080 8gb - GPU
• Ryzen 7 1700x - CPU
• (1) SSD, (1) 5400 rpm HDD
• Gigabyte x370 k7 mobo
• 6 140mm case fans
• 27" monitor with keyboard and mouse

• 550w SeaSonic G 80+ Gold

As far as my desire for overclocking, since I am just delving into the vast world of PC knowledge, I will wait until I am a bit better acquainted to do much OC. However I would like to leave myself room for OC, don't know if I ever would go for an SLI setup for this build. Im going to be using the computer mostly for multi-threaded tasks, and am quite excited, coming from a MacBook Pro, for the extra oomph. With that said, the computer will commonly be at a high load and I will potentially want to push it further in the future with overclocking.

So basically I have three questions

1) Would 550w be enough for my current set up with some OC headroom or should I return the PSU I have an upgrade to a 600+ watt unit?

2) Im assuming 550w would be too low for a future SLI setup, would a 650w unit be a better investment to take into account future additions or possibly even more power?

3) What could exactly happen if the computer demanded more power than the PSU could deliver? would that cause any part of the PC to become damaged in result or do PSUs have some sort of safe guard against that?

Thanks for the time
Ive seen calculators with a 300 watt difference in readings, people suggesting 750+ watts and others even suggesting 1000+ watts for similar builds. I figured it was overkill but seeing such a great amount of conflicting answers had me well.... conflicted!

 

[NDC1995]

550w should be ok.

If you will want multiple highend gpu's installed, then yes, you will need to go over 600, 800, 1000 W.

For just 1 GPU , 550 W is confortable.

Some sugest a higher rating PSU either because of future adition of a GPU (u allready got 1080 ... i don't see much point to adding more, few games take advantage of multiple GPU, even fewer of DX12, so spending 700$ for 3-5 fps improvement in most games does not make much sense IMHO) or because, sometimes, what is written on the box of cheaper PowerSuplies is not actually what they deliver. It syas 500 on box but u can get closer to 300 in some cases. That should not be a problem with Seasonic.

Regarding OC... If you can OC a single GPU and a CPU to draw over 550W, you should be more worried about cooling. GTX might take it, but older AMD CPUs (not sure if it applies to ryzen, but my gut says yes) would under no circumstances survive heavy OC with stock cooler.

I strongly doubt that you can OC your setup to draw so much power.


If the computer needs more power than the PSU can deliver it will become unstable (freezing, crashing) under heavy load (gaming). Continued strain will eventually fry the PSU (and if your components are cheap, could also drag one into the grave with it).

 

[Makentox]

1. 550w will be more than enough for current build + seasonic products offer good quality.
2. To be 100% sure i would get at least 750W for SLI setup, it will also give headroom for future upgrades. Dont forget that overclocking will suck more power out of it.
3. Most often your system will be unstable, crush, instantly shutdown, overheat (or worse if bad quality PSU). Getting close to PSU limit will make its fan work louder if you care.

 

[n0ns3ns3]

SLI for gaming is pointless waste of money with too many issues these days.
550w Seasonic G will be fine with your system even overclocked. if you really push the limits with overclock and run some synthetic load on both CPU and GPU simultaneously, a total system power draw can be in 450w range. I'd feel more comfortable with 650w unit, but that's really not a "problem".
If you do want to have an SLI, target 850w of a good unit.

 

[Isokolon]

There's a lot of rumours going on about PSUs
There was the rule of getting twice as much power as you can draw (hence the 1000W suggestions)
While this might have been true at some point in history it isn't anymore.
Quality PSUs can safely draw almost their full wattage continuously without problems and are usually capable of withstanding higher loads even without failing. The lower the quality of the PSU the less true this statement becomes though.

Your CPU is rated for 65W
Benchmarks show that a puristic system with a 1800X without GPU draws up to 150W (board, ram, 1 drive, CPU, air cooled)
Starting from this figure (which is safely far more than your CPU would draw) we can add the power draw of the 1080, which won't exceed 250W (typically the 1080s draw around 200W tops)

So a 550W PSU will supply enough power at generous stock speeds for your system.
Depending on how much you're looking to overclock, if you're planning on getting a liquid cooler and/or a bunch of case mod stuff and lights and depending on how noise sensitive you are you might want to consider a 650W unit, but it's not really necessary.

For a SLI Setup on the other hand, a 750W unit would be my choice as 650W can work but can get close.

As for 3) it depends on your computer.
Some PSUs allow some overload (and aren't exactly dangerous), others simply shut down to protect your components.
Again it's a matter of quality. A quality supply should shut down before anything happens to your system. A junk unit might blow up and burn your house down in the process.
In between there's a huge space of different things. It could be that the power delivery isn't stable anymore and you're running in a lot of hangs or bluescreens, general system instability or PSU failure. That's why it's important to pick a quality unit. The selected Seasonic G should be of sufficient quality for your needs.

 

[raisonjohn]

1) The 1700X roughly consumes 95W (based on TDP) of +12V power, but can go ~30W over TDP when OC'd, or ~125W. The MSI GTX 1080, depending on exact model, assuming the Gaming X model that requires a 6-pin and an 8-pin PCIE power connector, can theoretically consume up to 300W (i.e. 75W via 6-pin + 150W via 8-pin + 75W via PCIe x16 slot). A typical HDD usually draws ~30W +12V during startup but operates mostly on the +3.3V during use. An SSD draws very minimal (almost negligible) power around ~3W or less. A couple of DDR4 RAM sticks would most likely see ~10W or less power draw at +12V. Typical 140mm case fans draw around 0.25A or 3W at +12V (depending on model), so having 4 case fans would draw 1A or 12W. Other components that are connected to your motherboard and PSU (such as CPU cooler, LED strips, etc.) and headroom/allowance can be estimated at another ~50W (assumption).

So, all in all, you'd be looking at around ~530W power draw at the +12V rail (or ~44A).

The Seasonic G-550 provides 45A at the +12V rail (total of 540W). Basing on the above estimated power draw and headroom assumptions, you would be using more than 95% of the PSU's power at full load. The PSU is still enough to power your rig but you might want to consider getting the 650W versions for more headroom and better efficiency.

2) As the 550W would be pushing it to the limits of your current single GPU setup, it definitely won't cut it for an SLI'd rig. A 650W would most likely suit your needs for a single GTX 1080. Going for SLI GTX 1080, just add ~300W to your current calculated setup, so, 530W (based on your current setup) + 300W (add another GTX 1080) = 830W draw at +12V rail at full/peak load. Getting the 850W to 1000W versions of a good quality PSU is highly recommended.

3) If using low quality PSUs, then, yes, damaging the PSU and other components is highly probablr. Higher quality PSUs have better capacitors and protections such as overvoltage (OVP), overcurrent (OCP), and some even with overtemp (OTP). The declared/rated wattage and amperage in those good quality PSUs are actually lower than what the PSU can actually provide (i.e., drawing 600W on a 500~550W good-quality PSU will still power your rig/components without damaging it). But it is always safer and more efficient to calculate based on what the official specs of the PSU are.

 

[4745454b]

Your CPU is rated for 65W

? I thought all the X Ryzen CPUs had a 95W rating?

1) Would 550w be enough for my current set up with some OC headroom or should I return the PSU I have an upgrade to a 600+ watt unit?

First, I doubt 50W is going to make that much of a difference. If 550W isn't going to cut it, I doubt 50W more will make much of a difference. Running stock you have a 100W CPU and a 200W GPU. Toss in a bit more for the rest of the system and I see your power draw around 350W. Now the tricky part. Some want their load to be ~50% of what the PSU can do, so they'll buy a 700W+ PSU. I'm willing to load a PSU up to 80% of it's total output. 437.5W, or a 12V rail(s) of 37A. This is what my 450W PSU can do. Second issue though is you said you want to OC. Every chip is different and some OC without touching voltages, but OCing adds uncertainty to this. Lets assume absolute worst case. We'll stick with that same 50W for the rest of the system, but lets bump the CPU up to 225W and the GPU up to 300W. I went with 225W not because I've seen data saying Ryzen can use that much, but because their old CPUs could. You are now looking at nearly 600W. You would now need AT LEAST a 750W, an 850W would be a better idea. ***If your eyes glazed over and you didn't follow the math, pay attention to this.*** If you want to run stock or do some MILD OCing, you are fine to use your 550W PSU. If however you seriously want to push that CPU and GPU to the absolute limit you'll need a bigger PSU. Not a 600W, but one MUCH bigger.

Im assuming 550w would be too low for a future SLI setup, would a 650w unit be a better investment to take into account future additions or possibly even more power?

There are only a few 650W PSU that can handle SLI of larger cards. And if you go with one of those then you are looking at no OCing. If the 1080 is a 200W card and you want to run two of them, you are already at 400W (stock.) JUST with the video cards. You'll be pushing 600W once you add in your CPU and rest of the system. I wouldn't try SLI 1080 on a 650W PSU.

What could exactly happen if the computer demanded more power than the PSU could deliver? would that cause any part of the PC to become damaged in result or do PSUs have some sort of safe guard against that?

This is going to depend on the exact PSU you have. It's called OCP or OPP. (Over Current/Power protection.) There is a preset "trip point" in the PSU (maybe) where if you cross that point the PSU will shut off. This is a good thing. There are many problems however. From reviews I've read sometimes the box claims there is OCP or OPP, but the trip point can't be found. Another issue is sometimes by the time you reach that trip point, dangerous voltages are being seen by things being powered by the PSU. You really don't want to get near the trip point.

Unless you want to max the OC, I'd stay with what you have. It's a good unit. You won't have the power to set any OC records but that's ok.

Edit: I obviously disagree with raison. He's using bad/incorrect figures for many of his things, and even adds another 50W for things you might not have. My entire "rest of system" is 50W, and that includes hdd, ram, etc.) 30W for spin up? A hdd uses a 12V motor to spin the disks, so it's used the entire time, not just start up. Looking at drives I have and online it uses 1A, or 12W when spinning max. 12W, not 30W. RAM sticks are like 2-3W per stick, or around 5W for a pair, not 10W. I lump all this together and call it 50W. He's also using a 300W for the GPU which as I mentioned above is for an OC'd 1080, not just any 1080. It "can" use that much, but most only come with an 8pin plug limiting it to 225W. And most only hit 300W when OC'd.