Identifying a Bottleneck?

[kinger8938]

I've never understood the act of bottlenecking. I get what it means roughly, but what are the signs to show it's happening?

I was Playing Control by Remedy last night. (Quite a demanding game) Pressing the middle button on the control pad brings up a beta game U.i from Microsoft and part of that shows usage in percentages for CPU, GPU and RAM.

I Pinned it so I could track it while playing. When I got in to a gun fight my CPU usage hits 100% and performance drops a bit. The GPU seemed to hover around 50-60% but I'll confirm that as I was .ore concerned about the GPU.

My specs are as follows
I5 2500k @4.5
GTX1070
16GB Ram.

Upon a bit of googling, I saw many folks talking about concerns with upgrading to this graphics card on my motherboard which I think is an Asrock Extreme 3 Gen3 with worries about maybe needing bios upgrades to support the card etc (I've never upgraded the bios, card plugged in and worked so I assume its fine)

Entry level stuff I know, go gentle on me any advice appreciated.

 

[MiKeOnE10110]

Might be worth trying to use higher settings in games, that's low usage for a gpu in a modern game. As for the high cpu usage is it a constant high or only jumping to 100% for a short time as that would be normal. If you're playing on a low resolution try using multi sampling or similar, also try to see if your problems are across multiple games and not just that one as it could be more demanding than others on the cpu.

 

[LuckyBenski]

I think the term is overused so take it with a pinch of salt. Here's what people are talking about though:

A game has to do two main tasks: compute the gameplay, and render the current state into graphics via the graphics card.

Computing gameplay is a CPU task and includes working out player movement, other objects' behaviour, health, etc. This is a fairly fixed task and so graphics settings won't affect it much. Some games have a big CPU load for instance when calculating lots of enemies' behaviour. Others don't.

Graphics processing is just that: taking the game state and drawing all the objects, applying textures and lighting etc. You can turn up things like resolution, complexity of shapes, texture detail, shadows etc to make it look better. All these things make more work for the graphics card.

The bottleneck lies when one process is limited by its hardware. This process then limits the entire game from being rendered and calculated any faster.

If the CPU can only calculate the game state 50 times per second, then no amount of graphics power can render more frames than that. This is where you'll see GPU consumption go down while CPU usage is close to 100% (or at least some cores are fully loaded, if the game isn't well multithreaded).

In this case you may as well up the resolution or graphics settings and "use up" the available graphics power. But you wont get any more frames.

The reverse can happen, CPU isn't fully loaded but the graphics card is saturated. This is technically a bottleneck too but people don't consider it a problem.

That got a bit long winded but in short - CPU performance can limit overall framerate. Sometimes it's down to available threads and sometimes it's down to single thread performance.

 

[Adam123]

I used to play on low settings (to get more frames in FPS games), however, noticed that my CPU usage was often 90%-100% while my GPU was at 20%-30%.

I changed my settings to High and now both CPU and GPU run at around the same load 80% ish with no noticeable difference in frames

 

[Audigex]

I've never understood the act of bottlenecking. I get what it means roughly, but what are the signs to show it's happening?

It's always happening... because a "bottleneck" just means the slowest component in your machine. Nobody has a perfectly balanced PC: there will always be one component that's running at less than 100% because it's waiting for another. In most cases that's the CPU waiting for the GPU, or the GPU waiting for the CPU - but it can also be either (or both) of those waiting for the memory, SSD/hard drive, or the network card etc.

So yeah, bottlenecking is always happening to some extent: even if you perfectly balance your PC so that the CPU and GPU are both at 98-100% in one game or task, another game or task will have different demands... so you will always have a bottleneck, because a bottleneck is just the component that the others are waiting for.

Bottlenecking is only a problem when one component is much slower than the others: for example I put my GTX1080 in my old PC this weekend because my current motherboard died: my old CPU was thrashing away while the 1080 was barely ticking over.... in that scenario, the old CPU was the clear bottleneck.

Bottlenecks only matter when speccing a new PC (so you can make sure you aren't wasting money on an expensive CPU that will just be sat around waiting for your cheap GPU), or when deciding what to upgrade next (there's no point upgrading your 2080TI if it's being bottlenecked by your 5 year old i3 CPU... you should upgrade the CPU instead)

I was Playing Control by Remedy last night. (Quite a demanding game) Pressing the middle button on the control pad brings up a beta game U.i from Microsoft and part of that shows usage in percentages for CPU, GPU and RAM.

I Pinned it so I could track it while playing. When I got in to a gun fight my CPU usage hits 100% and performance drops a bit. The GPU seemed to hover around 50-60% but I'll confirm that as I was .ore concerned about the GPU.

My specs are as follows
I5 2500k @4.5
GTX1070
16GB Ram.

Upon a bit of googling, I saw many folks talking about concerns with upgrading to this graphics card on my motherboard which I think is an Asrock Extreme 3 Gen3 with worries about maybe needing bios upgrades to support the card etc (I've never upgraded the bios, card plugged in and worked so I assume its fine)

Entry level stuff I know, go gentle on me any advice appreciated.

So applying the above description to your scenario: Your CPU was at 100% and your 1070 was idling. That means your CPU was working as hard as it could, but your 1070 still had spare capacity. In this scenario, your CPU is the bottleneck. Which means that if you want to upgrade your PC, you should upgrade the CPU

That makes a lot of sense because your 2500k is an 8 year old CPU, and was only a mid-range chip when new... whereas your GPU is a 3 year old design and was at the top end of mid-range. The 2500K was (and still is) an excellent little mid range CPU that punches well above it's weight, but it's not entirely surprising that it can't keep up with a nearly-high-end GPU that's 1/3 it's age.

Now, bottlenecks aren't something you need to deal with urgently: it just means that your 1070 isn't being used to it's full potential, and that if you want to upgrade your PC, upgrading the GPU would be a waste of money. Next time you're upgrading your PC, get yourself a new CPU (and probably motherboard) and it will either match your 1070, or exceed it... at which point your 1070 will become the new bottleneck and you'll eventually replace it with something more powerful

If you don't have the money to upgrade, no problem - your bottleneck isn't doing any harm, it's just limiting your performance to whatever your CPU can keep up with.

To some extent, you can balance bottlenecks with graphics settings: the CPU is handling the game updates (some physics, and things like decision making), so that load is mostly fixed - but you can increase/decrease graphics settings to match your GPU. In your case, you have spare GPU capacity - so you can probably increase graphics settings (just not numbers of objects/render distance etc) to some extent.

 

[BUDFORCE]

See if you can ebay a second hand i7-2600k and overclock it.

Probably make a nice difference for little money, guess it depends if you can find one that works for cheap enough.

Otherwise your CPU is getting on, so either put up with it or its a new motherboard/CPU/RAM combo for you.

 

[kinger8938]

See if you can ebay a second hand i7-2600k and overclock it.

Probably make a nice difference for little money, guess it depends if you can find one that works for cheap enough.

Otherwise your CPU is getting on, so either put up with it or its a new motherboard/CPU/RAM combo for you.

That's an angle I hadn't considered actually!

I'm looking to rebuild the PC based around a Ryzen 3600 asap, pretty much just keeping the 1070 and my storage. So hopefully it will make me notice a difference. But will a 3600 then be too much for this card?

 

[Audigex]

That's an angle I hadn't considered actually!

I'm looking to rebuild the PC based around a Ryzen 3600 asap, pretty much just keeping the 1070 and my storage. So hopefully it will make me notice a difference. But will a 3600 then be too much for this card?

Depends on the game but it should be a reasonable match for most usage

There are two ways to look at this: you can either try and perfectly match your CPU upgrade to your GPU... which will mean you aren't over-spending on the CPU right now for performance you won't use, and get maximum benefit from your newest component. The downside being that once the system gets slow, you're going to have to replace the CPU and GPU at the same time, which will be expensive and mean you probably don't get as big an upgrade. It also means that you'll get a less powerful CPU to pair with your 1070, so in CPU-only tasks, your PC will be slower, although you'll save a little money now.

Or alternately you can buy a CPU now that is overkill for your graphics card. You'll waste a little potential in your CPU for a while (like you've been wasting the potential of your GPU recently), but the flip side is that in a couple of years when your GPU gets too slow, you can just upgrade the GPU

Personally I prefer the latter "bunny hopping" approach: replace the CPU/Motherboard, then a couple of years later replace the GPU, then a couple of years after that the CPU/Motherboard again. That way I'm spending perhaps £400-500 every couple of years, rather than £800-1000 every 4 years... I find it's more manageable to do the former, because it's easier to pull together and justify £500. I tend to then throw a PSU, storage, or case upgrade in every now and again, which means I eventually refresh my whole PC

Which approach suits you is likely to be down to preference.

Just remember that there will *always* be a bottleneck, and that you don't need to try to balance things perfectly.