RTX 4090 CPU Bottleneck & Stuttering

[VPalermo]

Hi All

My main PC is an i7 12700k with 32 GB 5600 MHz DDR5 RAM and MSI Gaming X Trio RTX 4090. It runs any game I throw at it buttery smooth at 4K high FPS without any stutter and only minor FPS drops which are unnoticeable due to Nvidia GSync.

My bedroom PC is a i7 10700k with 32 GB 3200 MHz DDR4 RAM and MSI Ventus RTX 4090. My bedroom PC runs the same 4K games anywhere from 20 - 30 FPS slower than my main PC. This is after enabling MSI’s game boost feature CPU overlock in the motherboard BIOS of my bedroom PC. Before enabling MSI game boost I was getting 30 - 40 FPS less on my bedroom PC than my main PC.

What’s most frustrating is that sometimes when the FPS drops the bedroom PC will intermittently stutter for a micro second in all the games I tested Witcher 3 next-gen, Cyberpunk 2077 and Watch Dogs Legion. My main PC does not stutter at all. The stuttering on the bedroom PC is intermittent and doesn’t happen all the time but it’s frustrating when it does happen. The intermittent stutter and frame drops are very noticeable despite having Nvidia GSync enabled.

I’m putting this down to a CPU bottleneck with the 10700k not being able to keep up with the mighty RTX 4090 but I’m surprised if that’s the case. Everyone is always saying that CPU bottlenecks don’t occur much at 4K resolution only at 1440p or lower. It’s the reason why most tech reviewers will only benchmark games at 1080p and 1440p not 4K.

The bedroom PC is a clean install of Windows 11 and the system passes 3DMark Timespy stress tests without any issues.

I wanted to check with you all if I’m right and this is definitely due to a CPU bottleneck? I really don’t want to shell out on a new CPU and motherboard but I might need to as gaming on the 10700k system with the RTX 4090 is unplayable and takes away the enjoyment of games.

Please let me know your thoughts? Any help or advice you can give me would be greatly appreciated.

 

[VPalermo]

Both systems running the game from an NVME rather than a SSD?

Thanks for the reply. Yes both running games from NVME SSD but the bedroom PC is only Gen3 NMVME where as the main PC is Gen4. Although I don’t think it matters because even though all of the games are installed on the Gen4 NVME on the main PC I just realised that Cyberpunk 2077 is running off of the SATA SSD and it still runs better than the bedroom PC which is a Gen3 NVME SSD.

 

[VPalermo]

Limit framerate and see if the stuttering still occurs

Thanks for the reply. Both TVs are LG OLED with HDMI 2.1 and 120hz refresh rate with native Nvidia GSync support. Should I limit the FPS to 119 or 120 on the bedroom PC?

 

[VPalermo]

Yes it's a very clear and obvious case of CPU bottlenecking. In truth even your 12700K isn't really strong enough to tame a 4090, but we can only wait for better. Presumably the 7700X3D is arriving by March and that should be the new king.

Thanks for the reply. Yeah I know what you mean. The new Raptor Lake chips are insane an i5 13600k is more powerful than an i9 12900k at gaming workloads.

However, I’m fine with the i7 12700k performance. I can buy a new Z690 or Z790 motherboard, not sure if i’ll go for a 12700k or 13600k yet.

Is it worth investing in a DDR5 capable motherboard or should I get DDR4? Since it’s my bedroom PC I’d prefer to save some costs if I can re-use my 32 GB 3200 MHz DDR4 RAM.

On the other hand if the DDR4 RAM will bottleneck and I’m shelling out for a new motherboard and CPU I’d rather go for DDR5.

 

[VPalermo]

Ignoring overclocking that 10700k is anything up to 40% slower than the 12700k, a chip that is already borderline for cpu bottlenecking a 4090.

Basically the 10700k isn't strong enough for the 4090 without some adjustments to allow for it's reduced performance. You can reduce stuttering by limiting framerates, lowering some settings etc.

Thanks for the reply.

Looks like a new motherboard and CPU it is then.

 

[VPalermo]

Yeh at 1080p or 1440p maybe, but at 4K i seen a video where it was like 3%/5%to10% difference compared to the 13700k even, no way it would be 40% difference lower, maybe in apps or blender, my 4090 if i can be bothered to install it, i will be using my 6700K even and will be ok, i mean it looses like 20% max at 4k in games even compared to a 13900k, loads of videos comparing games with the 4090 vs 13900 vs right down to 6700k even, every cpu is bottlenecked against the 4090, at 4K gaming not a lot difference, im happy to use my 6700K at 4K with my 4090 until i get new cpu and motherboard.

That video makes no sense. Are those benchmarks legit or faked? My 10700k is at least 30 - 40% slower when paired with an RTX 4090 compared to my 12700k.

Although none of those benchmarks in that video are using ray tracing. All the games that I am playing are with ray tracing and DLSS enabled.

 

[VPalermo]

Watch Dogs Legion RTX 4090 DLSS ON 4K

Watch Dogs Legion RTX 4090 DLSS ON 4K everything on FULL

youtu.be

This guy has a slightly better processor than me 10850k vs 10700k and RTX 4090.

His performance in Watch Dogs Legion is only slightly better than mine.

The only other major difference is that he is playing with DLSS set to Balanced and I am playing with it set to Quality.

It’s definitely a CPU bottleneck I’m sure of it.

 

[VPalermo]

Have you made sure you've got resizeable bar enabled on the older system?

I’m sure re-disable bar is enabled but I’ll have to double check.

Thanks to all who have replied to this thread trying to help me!

 

[VPalermo]

I’m sure re-disable bar is enabled but I’ll have to double check.

Thanks to all who have replied to this thread trying to help me!

I checked and re-sizeable bar is enabled!

 

[VPalermo]

What psu are you using on the bedroom PC?

Reason I ask is because up until recently I was running a 4090 with a 9700k on a 4k Oled and it was buttery smooth playing everything except Red Dead Redemption 2 and Assassin's Creed Odyssey, which had problems with stutter. I knew when buying the 4090 that my psu may not be powerful enough but I decided to give it a try first before splashing out on a new one. But when the stutters appeared I didn't think twice about upgrading the psu, which completely sorted the stutter issues out.

I've since upgraded to a 13700k and to be honest at 4k there's next to no difference to the 9700k in any of the games I play.

So yeah, there should be no reason a 10700k should bottle neck a 4090 running at 4k, to the point where it's causing any issues with stuttering, not if a 9700k doesn't anyway.

Hmm that’s odd.

Both PC’s have Corsair 1000w PSU’s. In fact the main PC is a much older model Corsair HXi1000 where as the bedroom PC is a new HX1000. So I don’t think the issue is with the PSU.

 

[VPalermo]

Setting the FPS limit to 118 FPS has definitely helped. The stuttering now only happens if the frames drop by 20 or 30 FPS intermittently.

I’ll probably go for a new motherboard and CPU in the new year.

 

[VPalermo]

i am having exactly the same issues at 4k with rtx 4090 and 13900k. i replaced the mobo and it did not help either. get these really random fps lows which cause stutter for me on my lg oled c2. mine is the gigabyte gaming OC. is yours?

No my GPU is an MSI Ventus. Also I managed to eliminate most of the stutter by capping the FPS to 118 frames. Now I just have a lower FPS than my 12700k system.

What CPU were you using before you got the 13900k?

You really shouldn’t be getting any stutter with a 13900k. Are you using DDR4 or DDR5 RAM and what speed, how much CL? Also what motherboard are you using? What size is your AIO? Are you running the AIO on default fan speeds or custom fan curve?