Main Thread loop. Realistic upgrade target for new CPU

User Support Hub Hardware & Peripherals
1

I have a quad core Xeon E31245 @ 3.3GHz, with a staggering 8MB L3 cache :grinning:
The GPU is a 1080TI, the motherboard is PCI 2.0

The Main Thread loop looks like it could improve a lot:

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So what is a realistic mid-budget target for CPU clock speed and PCI bus? Am I correct that PCI 4.0 won’t make a big difference for the GPU?

This month in the UK the Ryzen 5800X looks to be good value with 8 cores, 4.6GHz boost and 36MB cache. Will that deliver the Main Thread improvement I should expect?
Obviously you can’t directly compare Xeon clock speeds with Ryzen clock speeds

I’ll use a B550 MB with 32GB in two slots, allowing for 64GB or 96GB in the future.

Thanks

2

If anything take the 5800X3D with 96MB cache. That’s certainly still a very good mid range CPU for MSFS

3

I agree the 5800X3D with the 96MB of cache is great, but the extra 60MB of L3 cache adds about 60% to the cost of a 5800X.

It would be interesting to see comparisons between the 5800X and 5800X3D.

4

Trust me:
I scaled “down” from a 5950X (!) to a 5800X3D before I switched to my current AM5 system, and the performance increase in MSFS was STAGGERING. I know it’s hard to believe since the only difference is a little L3 cache, but MSFS is one of those applications that does make serious use of that extra cache and among all the AM4 processors the 5800X3D is a real gem!

I promise you: you will regret it, if you go with only the 5800X.
If you currently don’t have the money to buy the 5800X3D wait till after Christmas. Prices usually drop then or check if you can score some BlackFriday/CyberMonday deal or get a used one on eBay.

(BTW: How can you have a Xeon with a B550 board?)

Edit:
Just remembered this thread:

It starts with this screenshot:

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5

Hmm, interesting. The 5800X3D cost per fps is higher than the 5800X. It would have to drop about 20% to be of equivalent value.

Maybe the X3D price has been kept high due to press popularity. Whereas the 5800X has already dropped in price.

As you said best to wait a little.

6

Btw The Xeon is on a Dell motherboard. It used to be a server in the company I worked for.

I will choose a new B550 board for the Ryzen.

7

I don’t have a side-by-side comparison, but I can say that going from a 5800X to a 5800X3D made a noticeable improvement. It ‘feels’ like I’m getting about 15% higher FPS, with about a 20% decrease in latency. It’s worth the money.

Another thought I had: Server motherboards generally use registered ECC memory. I suspect that hurts the sim’s performance. I have an MSI B550A-Pro. It’s on the low-end, but I bought it because of tests mentioning its robust VRM. I think less capable motherboard VRM’s are responsible for a lot of the ‘unexplained’ CTD’s in this sim.

8

I’ve read that the 5800X3D runs much cooler with the voltage reduced by 0.05V
That sort of indicates a stable VRM is important.

9

My MSI BIOS has a three-level ‘Kombo Strike’ option. I haven’t dug into the voltage numbers, and MSI is tight-lipped about exactly what it does. I use Level 2, and my liquid-cooled 5800X3D runs around 63°C in the sim.

I decided to grab an EKWB GPU water block on a clearance sale, and a Thermalright Assassin 120 air-cooler for the CPU. I’ve got the air-cooler mounted, and will reroute the water pipes to the GPU this weekend. It will be interesting to see how both components’ temps change. One thing is for sure - my chassis temps will get better. The air-cooled GPU was a furnace.