Odd question, and I know the real answer is "Just buy a complete new rig", but for various reasons, I want to try to get some more life out of my current motherboard and GPU.

I'm currently running a B450 Tomahawk Max with a 3700X.

I can get a 5800X3D *really cheap* (second hand but barely used) - no concern over age, wear and tear etc. I also have a cooler that will work fine with it (Dark Rock TF2).

I'm aware that it's only a PCIe3 board and that I'll be leaving performance on the table and I'm okay with that.

That being said, I'm currently worried about RAM compatibility. Looking at the list for the motherboard, it looks like the compatibility for 5 Series Ryzens looks really low:

https://www.msi.com/Motherboard/B450-TOMAHAWK-MAX/support#mem

I'm currently running some Corsair chips that aren't great (Corsair Vengeance LPX 16 GB (2 x 8 GB) DDR4 3466 MHz C16 XMP 2.0), but work fine with my 3700X.

So, for my specific case (B450 Tomahawk Max, keep the RAM, upgrade to a 5800x3D), does anyone have any idea whether this will work or whether I could run into problems? I know that the RAM lists are usually based on whatever the manufacturer could be bothered to test, but I don't want to go through the faff of swapping in a CPU and cooler only to have to either switch it back or find chips on the tiny compatibility list for the 5 series processors.

Again, just for the avoidance of doubt "buy a new motherboard and RAM" doesn't answer the question I'm asking here ;)

I am not techy enough to really answer your question but just wanted to say every tech site I follow screams about how sensitive Ryzen is to poor RAM and bad RAM settings.

1st gen was touchy, but ram compatibility has gotten much better afacit. That looks like slow-ish ram so it's not like you're pushing things to the limit. Worst case, you can always fall back to lesser timings. I'd say you have nothing to worry about.

Yeah - I mean it works on the same board with the 3700x. It's just the way that Corsair (and a load of other brands) are missing from the compatibility list for the "5" memory controllers that ran up a red flag. I'll probably also ask over at Tom's...

It is likely that the corsair RAM you currently have will work with the Ryzen 5800X, even through it is not on the MSI compatibility list for 5 series Ryzen processors. The compatibility list is not exhaustive and is based on what the manufacturer has tested, so there may be other RAM modules that work well but are not listed.

What arjun_suhass_lub wrote.
I was in the same situation as you back then when I was shopping RAM for my 2600X's when I stumbled on the comment's section of the memory I eventually ended up buying over at newegg. There were a few folks with the same MB reporting full compatibility, I bought it and never had a problem so far.

You just need to look for info and eventually youi'll find all the answers.

I have tried - it's just an odd use case (already have the RAM, motherboard and using a 3 series CPU on it), just trying to upgrade the CPU.

I'm inclined to just give it a go and see what happens. Worst case I just drop £150 on a B550 Tomahawk and go through the pain of changing the board as well, although I would rather avoid this.

I also realised I got my RAM wrong because I was being an idiot - it's actually 3466 Mhz rather than 2400.

It's difficult to say for certain whether your current RAM will work with the 5800X, as compatibility can vary even within the same model of RAM. However, there are a few things to consider:

First, the official compatibility list from MSI is not exhaustive, and there may be other RAM modules that will work even if they're not listed. You could try looking up user reports or reviews of the B450 Tomahawk Max with a 5800X to see if anyone has had success with similar RAM.

Second, even if your current RAM isn't officially supported, it may still work, but at a lower frequency or with looser timings. This might not be ideal for maximizing the performance of your new CPU, but it could still be a functional solution.

Finally, if you're willing to take a risk, you could simply try installing the 5800X and see if your current RAM works. There's a chance it won't, but if it does, you've saved yourself the trouble of buying new RAM.

Overall, the safest and most reliable solution would be to purchase RAM that is officially supported by MSI for the B450 Tomahawk Max with a 5800X. However, if you're willing to take a risk and potentially sacrifice some performance, it's possible that your current RAM could work.

Yeah - I've been using it with the XMP profile activated, so it's running at full speed.

I think I'll give it a go and just get the new processor. I mean, the memory controller in the 5800X3D hopefully isn't going to be any worse than the one on the 3700X. Worst case scenario, I'll have to either get new RAM or upgrade to a B550, but let's hope not.

A trailer truck is going to cost a lot more than a computer. Don't buy a rig. They're not very good for gaming.

Anyway, don't buy any used computer hardware. You don't know what the previous owner did to it.

While I'd generally agree with you, in this case it's not buying from someone on ebay - it's a private sale from someone I know in person and I know how they the person used it. It hasn't been run ragged, hasn't been OC'd, lived in a well ventilated case with a good cooler and was hardly used.

But yes - if I didn't know all that, I wouldn't touch it.

Very nice BIG BOOBS = > amigoxxx.tk

You're a big boob.