CPU Upgrade advice

Craig006

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Sep 22, 2019
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I'm currently trying to iron out some performance issues with my PC.

i7 4790k clocked to 4.8ghz
RTX 2070 Super
16gb 1600 ram
Oculus Rift S

I can play fine solo but adding AI starts slowing things down. I maxed 23 ai players in donington park for my tests. The worst performance is with all AI using ginetta gt cars (from a mod). Using any stock ac cars, even with a wide range of liveries seems to perform better.

Solo on the track I get constant 80fps with no drops and adding basically any AI will cause the drop to 40fps, with 24 Ginettas on the track performance can dip down to 20fps, . After a lap or two with this horrible fps I notice that the CPU and GPU have both been hovering around 50-60% (on all cores for CPU). I would have expected either the CPU or GPU to be maxed, this issue seems to be mentioned in a number of threads. I turned off hyperthreading in the bios and reran the test and this time the CPU was maxed at 100%. My assumption here is that the CPU is the bottleneck and with hyperthreading scheduling tasks across real cores and virtual cores it makes it seem like the cpu is not the bottle neck. I could be wrong here though...

Anyways, what modern day CPU would be a good upgrade to the 4790k? I would be in for a new mobo, ram and cpu so would prefer not to go for the very high end. Is there a good bang for buck cpu that would kill the 4790k?

Otherwise, what else could be choking the performance when I add AI? I totally understand that I can drop AI count and graphics to improve the problem, but I'm hoping to identify the hardware issue and a possible upgrade. Maybe I can get to 80fps with good settings and 12 AI.

Would appreciate your thoughts :)
 

robt100

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Aug 6, 2011
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I would be in for a new mobo, ram and cpu so would prefer not to go for the very high end. Is there a good bang for buck cpu
I think that sentence pretty much says go with AMD. Most tech reviewers seem to suggest the latest gen Ryzen chips are best bang for buck.

An R5 3600 would be about 15-20% single thread improvement, but multi-threaded would thrash the 4790k, especially with 2cores/4threads extra. There's also an upgrade path to the next gen Ryzen when it is released (im assuming in around 12months time).

Though, im a little worried at the drop you get adding AI, even my ancient fx6300 can hit 40-45fps with AI. Are your graphics settings all set to epic??
 

Terry Rock

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Oct 24, 2009
2,247
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I'm currently trying to iron out some performance issues with my PC.

i7 4790k clocked to 4.8ghz
RTX 2070 Super
16gb 1600 ram
Oculus Rift S

I can play fine solo but adding AI starts slowing things down. I maxed 23 ai players in donington park for my tests. The worst performance is with all AI using ginetta gt cars (from a mod). Using any stock ac cars, even with a wide range of liveries seems to perform better.

Solo on the track I get constant 80fps with no drops and adding basically any AI will cause the drop to 40fps, with 24 Ginettas on the track performance can dip down to 20fps, . After a lap or two with this horrible fps I notice that the CPU and GPU have both been hovering around 50-60% (on all cores for CPU). I would have expected either the CPU or GPU to be maxed, this issue seems to be mentioned in a number of threads. I turned off hyperthreading in the bios and reran the test and this time the CPU was maxed at 100%. My assumption here is that the CPU is the bottleneck and with hyperthreading scheduling tasks across real cores and virtual cores it makes it seem like the cpu is not the bottle neck. I could be wrong here though...

Anyways, what modern day CPU would be a good upgrade to the 4790k? I would be in for a new mobo, ram and cpu so would prefer not to go for the very high end. Is there a good bang for buck cpu that would kill the 4790k?

Otherwise, what else could be choking the performance when I add AI? I totally understand that I can drop AI count and graphics to improve the problem, but I'm hoping to identify the hardware issue and a possible upgrade. Maybe I can get to 80fps with good settings and 12 AI.

Would appreciate your thoughts :)
What motherboard are you using and do you have your fastest harddrives linked up with your fastest controller?
I cannot tell you how many times I've had somebody state that their system wasn't cutting it, only to find that they simply plugged a drive into the first socket that'd work
 

Jeremy Ford

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Apr 28, 2016
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You're definitely running the graphics settings too high in VR. Adding AI is adding complex objects to be rendered on the track. Try lowering the in-game graphic settings and super-sampling. Start with low settings and work your way up. As a reference point, it's unlikely you will be able to run any setting above medium. Expect a mix of low and medium settings across the board.
 

Craig006

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Sep 22, 2019
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I think that sentence pretty much says go with AMD. Most tech reviewers seem to suggest the latest gen Ryzen chips are best bang for buck.

An R5 3600 would be about 15-20% single thread improvement, but multi-threaded would thrash the 4790k, especially with 2cores/4threads extra. There's also an upgrade path to the next gen Ryzen when it is released (im assuming in around 12months time).

Though, I'm a little worried at the drop you get adding AI, even my ancient fx6300 can hit 40-45fps with AI. Are your graphics settings all set to epic??
They are pretty high (not epic though, I'm also not in ACC, just normal AC... I just cant get ACC playable on my PC with VR... but thats another story), I'm trying to get to get to the best visual fidelity I can. 15-20% doesn't sound like a great result for the investment.... I wonder if the increased ram speed might improve that number? or is that like an overall guestimate?


What motherboard are you using and do you have your fastest harddrives linked up with your fastest controller?
I cannot tell you how many times I've had somebody state that their system wasn't cutting it, only to find that they simply plugged a drive into the first socket that'd work
I will double, thanks for the tip... (I just plugged it in)

You're definitely running the graphics settings too high in VR. Adding AI is adding complex objects to be rendered on the track. Try lowering the in-game graphic settings and super-sampling. Start with low settings and work your way up. As a reference point, it's unlikely you will be able to run any setting above medium. Expect a mix of low and medium settings across the board.
Something does not add up though, if its rendering issue I would expect that to be using gpu and the gpu is not close to 100%? I will try dropping back down to low and lifting settings until I see the performance drop again. Maybe that highlights something
 

Terry Rock

2000RPM
Oct 24, 2009
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"They are pretty high (not epic though, I'm also not in ACC, just normal AC... I just cant get ACC playable on my PC with VR...but thats another story)"....
You have something very wrong in your system if ACC won't run.
I went to the I5 2600X from an I7 3820 simply because I wanted to play around with video transcoding.
Every single ACC video on my YT channel up until Dec 10th was done with that 3820...some under the Rift CV1.
http://www.youtube.com/user/Saabjock/videos?view_as=subscriber
Your I7 4790k is a way more capable CPU than that I7 3820.
It should run ACC with no issue.
 
Last edited:

RasmusP

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Oct 7, 2016
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Best bang for the buck for single thread limited games like simracing titles is the i5 9600k when it's overclocked. And it overclocks easily!

2 friends of mine had the 4790k and were limited in all simracing titles.
One went for the 8700k and overclocked it to 4.9 GHz, the other one got the 9600k which runs at 4.8 GHz.

One has 90 fps in all titles in VR apart from ACC with very high settings, the other one runs at 160 fps on his monitor.

Before that one couldn't keep constant 90 on VR in AC or rF2, the other one had fluctuating fps from 90-130.

The AMD ryzen are good but still not there with single thread performance. For everything else than simracing they are better bang for the buck than the Intels though.

With AMD, faster ram is important, with Intel not that much.

My advice:
Gigabyte z390 elite or pro
Some ddr4 3200 cl16
I5 9600k

Then let everything on default in the bios but change the max turbo to 50/50/49/48/48/47.
That way you don't get an automatic increase in voltage that you should have an eye one but the cpu clocks nicely up to 5 GHz.

Should do the job and blow your 4790k out of the water :)

About fps on ac:
The graphic settings mainly hit the graphics card but for the CPU there are a few important things:
- objects, called "dri" AFAIK. Basically polygon count
- shadow calculation
- reflection calculation
- mirrors

So world details, car mods that aren't as optimized as the kunos cars, mod tracks etc all hit the CPU!

AI runs on the CPU and the polygons of the cars too, ofc.

Problem is that this all runs on 2 big threads and a few little threads.
Your CPU has 4 cores. In theory you would be stuck at 50% CPU usage because 2 cores would do nothing.

But there are tricks and windows shuffles the load across all cores etc.

In the end you can spike to 100% CPU usage with 4 cores but at 8 cores/thread with hyperthreading you see the mentioned 50-60%.

With a 8 core / 16 thread CPU you would see 50 and 25% with HT on/off.

You're still limited by the power of 2 cores.
Or rather be the power each single core has.

So if you want to know the best cpu for you:

Look for single thread benchmarks and pick a cpu with at least 6 cores to have some headroom.

As you'll see the 9600k, 9700k and 9900k will have the same single thread score with the difference of not running at the same clockspeeds!
But if you overclock the i5 to the speeds of the 9900k you'll basically have the same scores.

All AMDs are slightly below this.

Here in Germany the 9600k costs less than the ryzeb 3600 but has a higher single thread score, doesn't need expensive ram and you get a really good motherboard for sub 200€ with massive VRMs to hit 5 GHz easily! :)
 
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Craig006

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Sep 22, 2019
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So I just did another round of testing. This time I lowered all my settings in AC to the lowest possible and turned off any graphics features I could (I think reflections/smoke/shadows/pp can be turned off, either way I turned off everything).

When open the game solo, and just stand still at the grid it maxes at 80fps (Rift S), BUT, using oculus debug tool I notice that I get a huge performance spike every 5-10 seconds, I dont know if this is maybe the debug tool itself causing issues.. I will hover at about 50-60% performance overhead, then bam, a bunch of dropped frames, a dip in frame rate and performance overhead will drop to -5-10%. Every 5-10 seconds. Joining the game without VR does not seem to show this issue.

With these super low settings if I add 23 other cars (same as above) and stand at the staring grid the performance drops to 40fps with huge amount of dropped frames (this is with aws disabled, but I think the min fps is 40 so it just drops what it can't render in time). as the other cars take off and slowly make their way out of view the fps climbs 40, 45, 50... 70, 80. Then it will sit at 80... until the cars move back into view... or even if I glance towards the direction of the pack of cars (Even though they're not visible/obstructed by barriers) then fps immediately drops to 40fps.

Crazy, I think next steps is to do a fresh install of windows.
 

dud

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Nov 23, 2016
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You can also improve the cars from the mod:
  • The easiest is to lower the resolution of the textures, that should help quite a bit already.
  • And you can add LOD levels with a tool like 3dSimEditor whatsitcalled.

Doing that can also be a fun learning experience. And the author of the mod might be interested in re-releasing it with your LOD levels.
 

robt100

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That does sound quite odd for AC. Although not in VR, I can pump out 80+fps all day long on my very old fx6300 and a 1660ti :O_o:
 

RasmusP

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That does sound quite odd for AC. Although not in VR, I can pump out 80+fps all day long on my very old fx6300 and a 1660ti :O_o:
VR basically halfs your fps, sadly..
You have 2 big threads and the VR extra load comes on top of the already bigger thread so your CPU limit becomes way worse.

It's ridiculous that AC in VR requires a better cpu than games like Assassins Creed odyssey.
Difference is multi threading... Assassins Creed can load 8 cores to 100%, AC puts it all on barely 2 cores...
 

robt100

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VR basically halfs your fps, sadly..
You have 2 big threads and the VR extra load comes on top of the already bigger thread so your CPU limit becomes way worse.

It's ridiculous that AC in VR requires a better cpu than games like Assassins Creed odyssey.
Difference is multi threading... Assassins Creed can load 8 cores to 100%, AC puts it all on barely 2 cores...
I'm guessing that's just down to the age of the game, back when having more than 2 or 4 cores was quite rare.
Then again, ACC does a good job of maxing all 6 'cores' on my fx6300 to 90% at all times. Looking forward to being able to afford a CPU upgrade!
 
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