PSU impact on gaming performance

[Fasauceome]

I've just started browsing the forums recently, so if you've seen a couple threads from me today already, it's because I'm struggling to find preexisting threads about my questions.

Anyway, I keep seeing people suggesting inadequate power supplies for lacking game performance, but this seems silly to me. I've had a power supply fail, and it was much more catastrophic than just some dropped frames. I'm wondering if such a thing is even possible, given my understanding of how the electrical systems in a PC work. From what I understand, "less voltage = lower clocks" is the alleged case.

[Snipergod87]

As far as I know only when the PSU die's or cant provide power, but in that case your FPS drops to zero because your system crashes completely.  Components like GPU's and CPU expect a certain amount of power, that cannot adjust on the fly to, "oh the power supply can only give me 80% of what I need so I will drop back to 80% of max power" they just crash the system.

 

Now unstable power supplies can lead to other major problems other than just crashing, if the power is dirty or unstable some components have a high chance of being damaged.

[BubblyCharizard]

stability could be an issue with an inadequate PSU as the power requirements can change every clock cycle

Edited July 11, 2018 by BubblyCharizard

[Fasauceome]

On 7/10/2018 at 8:51 PM, Snipergod87 said:

As far as I know only when the PSU die's or cant provide power, but in that case your FPS drops to zero because your system crashes completely.  Components like GPU's and CPU expect a certain amount of power, that cannot adjust on the fly to, "oh the power supply can only give me 80% of what I need so I will drop back to 80% of max power" they just crash the system.

 

Now unstable power supplies can lead to other major problems other than just crashing, if the power is dirty or unstable some components have a high chance of being damaged.

that's basically what i thought. components will just always be asking for a certain amount of power.

 

On 7/10/2018 at 8:52 PM, BubblyCharizard said:

stability could be an issue with an inadequate PSU as the power requirements can change every clock cycle

on enough of a scale to flat out reduce framerate? not just by a little either, people suggest this for woefully terrible performance.

[BubblyCharizard]

10 minutes ago, fasauceome said:

on enough of a scale to flat out reduce framerate? not just by a little either, people suggest this for woefully terrible performance.

yes and no.....it all depends on what the CPU/GPU was doing when it wasn't getting adequate power delivery

 

it could be just as simple as a bit of stuttering or a full blown BSOD

[Fasauceome]

2 minutes ago, BubblyCharizard said:

yes and no.....it all depends on what the CPU/GPU was doing when it wasn't getting adequate power delivery

 

it could be just as simple as a bit of stuttering or a full blown BSOD

I know voltage ripple is a thing but to that extent?

[BubblyCharizard]

it was enough to cause major issues on my old x5650 xeon system enough that I had to disable 2 cores to get it stable again then I bought a new PSU and it worked perfectly again

[KarathKasun]

Voltage ripple has no effect other than stability/overclock headroom.

 

If the 12v line drops too much, some GPUs/CPU can downclock.  But the usual response to a very low 12v line is a crash because it interferes with proper voltage regulation.

[Fasauceome]

1 minute ago, KarathKasun said:

Voltage ripple has no effect other than stability/overclock headroom.

 

If the 12v line drops too much, some GPUs/CPU can downclock.  But the usual response to a very low 12v line is a crash because it interferes with proper voltage regulation.

that makes sense to me, which makes me wonder why I see so many people equating gpu to performance

 

[KarathKasun]

On 7/10/2018 at 9:34 PM, fasauceome said:

that makes sense to me, which makes me wonder why I see so many people equating PSU to performance

 

Idiots with too much money and not enough sense.

 

For an example of how much the PSU really doesnt matter...

 

I have some CB15 scores that are higher than the top HWBOT scores for an air cooled FX 4100, accomplished with a Thermaltake TR2-430 (430w, garbage design from ~2003) from ~2008.  Hell, I also put two RX 560's in that system for the lulz.

 

Review of the PSU HERE.

[STRMfrmXMN]

If the vreg is really, really bad, like wildly out of ATX spec bad, then sure, it can cause performance issues with your GPU not being supplied enough power. Typically though, your PC is rendered completely unusable by a faulty PSU. 

[Stefan Payne]

7 hours ago, fasauceome said:

Anyway, I keep seeing people suggesting inadequate power supplies for lacking game performance, but this seems silly to me. 

It is.

There are things a shitty PSU can cause like random freezes, lockups, reboots but shitty performance probably not.

[Amazonsucks]

44 minutes ago, Stefan Payne said:

It is.

There are things a shitty PSU can cause like random freezes, lockups, reboots but shitty performance probably not.

Instability and crashes would fall in the "shitty performance" category.

 

Also, CPU and GPU boost are power and thermal headroom dependent so if you have bad power then you probably wont have maximum performance either...

[Stefan Payne]

8 minutes ago, Amazonsucks said:

Instability and crashes would fall in the "shitty performance" category.

No, that is stability.

Has nothing to do with performance.

 

8 minutes ago, Amazonsucks said:

Also, CPU and GPU boost are power and thermal headroom dependent so if you have bad power then you probably wont have maximum performance either...

Why? What should cause that? I don't understand what you are trying to say, care to elaborate?

[Amazonsucks]

7 minutes ago, Stefan Payne said:

No, that is stability.

Has nothing to do with performance.

 

Why? What should cause that? I don't understand what you are trying to say, care to elaborate?

Modern CPUs and GPUs(Kepler and newer) have a base clock(guaranteed) and a boost clock(dependent on available power and thermal headroom).

 

Meaning, if your PSU is a POS and cant give the CPU or GPU the power it needs to boost beyond its base clock and remain stable, it wont.

 

And for me, stability and reliability is definitely part of overall performance. If its "high performance" but in the shop more than its on the road, it doesnt do me much good.

[Stefan Payne]

1 hour ago, Amazonsucks said:

Modern CPUs and GPUs(Kepler and newer) have a base clock(guaranteed) and a boost clock(dependent on available power and thermal headroom).

Yes, I know and how should a PSU influnece that??

 

1 hour ago, Amazonsucks said:

Meaning, if your PSU is a POS and cant give the CPU or GPU the power it needs to boost beyond its base clock and remain stable, it wont.

And how should that work?!
I don't see that happening

If a PSU can't deliver the Power, it switches off, hard. Or the Voltages go out of spec and the system crashes or shuts down.

The "can't deliver power, therefore slows down" is just bullshit. That can't happen as no ATX PSU is current limited other than a supervisior that switches it off.

 

1 hour ago, Amazonsucks said:

And for me, stability and reliability is definitely part of overall performance. If its "high performance" but in the shop more than its on the road, it doesnt do me much good.

Its two different things.

 

When you have a car thad toes 0-100km/h in 5s, that is perfrmance.

When the Engine or transmission blows up evers 30kkm, that is reliability.

 

Those are two completely different things that have NOTHING to do with each other.

[Peskanova]

From what I've experimented , a faulty psu main thing that can do is to break components or shut down your pc, It can break things like mobo (starting for faulty usb conectors , led's not turning on...) but things like "I turn my computer on and it shuts down a few times till boot" , or "suddenly my computer turns off 2 or 3 times per day" or coil whine (with a 5.1 sound system its easier to listen that or poppings) -> 99% psu related

I had a few faulty's crap psu (till i bought a decent one) gpu and mobo is the first to fail. and random shutdowns the first to hapen

[KarathKasun]

8 hours ago, Amazonsucks said:

Modern CPUs and GPUs(Kepler and newer) have a base clock(guaranteed) and a boost clock(dependent on available power and thermal headroom).

 

Meaning, if your PSU is a POS and cant give the CPU or GPU the power it needs to boost beyond its base clock and remain stable, it wont.

 

And for me, stability and reliability is definitely part of overall performance. If its "high performance" but in the shop more than its on the road, it doesnt do me much good.

GPU/CPU cant communicate with the PSU to know how many watts its capable of outputting.  Turbo/Boost rely on sensors built into the GPU PCB or Motherboard to provide feedback for clock tuning.

 

Power targets are based on what the part is specced to pull compared to how much the part is actually using.  So... if the GPU/CPU is better than average, it uses less power.  The boost algorithm can detect its power draw being less than spec, so it cranks up the clocks/voltage until it reaches the next limiting factor (usually voltage).

[Amazonsucks]

12 minutes ago, KarathKasun said:

GPU/CPU cant communicate with the PSU to know how many watts its capable of outputting.  Turbo/Boost rely on sensors built into the GPU PCB or Motherboard to provide feedback for clock tuning.

 

Power targets are based on what the part is specced to pull compared to how much the part is actually using.  So... if the GPU/CPU is better than average, it uses less power.  The boost algorithm can detect its power draw being less than spec, so it cranks up the clocks/voltage until it reaches the next limiting factor (usually voltage).

Right so if the PSU cant give the chip the power it needs... what happens? It wont boost.

[KarathKasun]

2 minutes ago, Amazonsucks said:

Right so if the PSU cant give the chip the power it needs... what happens? It wont boost.

No.  The PC shuts off.

 

The GPU doesnt know if the PSU can or cant supply the power.  Electricity does not work like you are stating.

[Amazonsucks]

4 minutes ago, KarathKasun said:

No.  The PC shuts off.

 

The GPU doesnt know if the PSU can or cant supply the power.  Electricity does not work like you are stating.

I realize that the PSU and the CPU and GPU dont communicate, but if the GPU cant get stable Voltage from the PSU its not likely to keep boosting until it causes an overload shutdown. If it does then thats a really bad PSU and a big design flaw.

[KarathKasun]

14 minutes ago, Amazonsucks said:

I realize that the PSU and the CPU and GPU dont communicate, but if the GPU cant get stable Voltage from the PSU its not likely to keep boosting until it causes an overload shutdown. If it does then thats a really bad PSU and a big design flaw.

Voltage droop is not really present on any modern PSU when you approach over current protection.

 

Old POS PSU rated at ~350w for 12v putting out ~400w on 12v still reads 11.75v (in spec).  It doesn't have over current protection, so it just keeps churning out power while its internals approach thermal breakdown temps.  GPU doesn't care that the PSU is about to pop, it still sees ~12v and is boosting away like nothing is happening.

 

Most PSU's will put out over their rated current if there is not OCP.  The question is how long until the diodes break down from the heat and some of that 120VAC hits your internal components.  If there is OCP, the GPU doesnt know about it and the system will power down to save itself.

[Amazonsucks]

Thats why im buying a Murata next time.

[Stefan Payne]

On 7/11/2018 at 1:26 PM, Amazonsucks said:

Right so if the PSU cant give the chip the power it needs... what happens? It wont boost.

Did you read what I was saying? 

Because that's bullshit.

If the PSU doesn't deliver the power, it will crash or switch off. Boosting has nothing to do with it, as PSU and GPU aren't communicating with each other...

 

On 7/11/2018 at 1:38 PM, KarathKasun said:

The question is how long until the diodes break down from the heat and some of that 120VAC hits your internal components. 

There are no diodes in many modern PSU no more
Its all done by MOSFETs, for better or worse (IMO worse because better efficiency, lower reliability)...

 

But you still do know your PSU Stuff, so thumbs up from me.

[KarathKasun]

1 minute ago, Stefan Payne said:

There are no diodes in many modern PSU no more
Its all done by MOSFETs, for better or worse (IMO worse because better efficiency, lower reliability)...

As far as I have seen there is still diode rectification on the high voltage side.