Ryzen 5 3400g/ Asus prime b450m bundle should I return it?

Welcome to the forum, @Melo. The ASUS B450M-A/CSM supported the Ryzen 5 3400G on BIOS version 1201, which was released on May 10, 2019. While not impossible, I find it extremely unlikely that one of our stores had a board on the shelf for over 1 year without it being updated. Did you run into a no-POST issue while assembling the system? Or are you checking out of precaution before building? 

You are more than welcome to bring the board back to the store for an exchange as I am confident our sales team will take care in making sure you have compatible hardware. If you want to attempt the build now to see if it works, we are here for you should you have any questions or issues.

When the 3000 series originally came out, we actively updated the BIOS on the 400-series boards we had in stock to make sure they were compatible, so even if it doesn't have the label it's pretty likely it's compatible. While it's not impossible, I'm going to agree with Mike and say that I'd be extremely surprised if we had a 400-series board in stock that did not have the proper BIOS update. 

The SSD you chose will work just fine in this motherboard. It has one PCIe M.2 slot available. 

Of course! Always happy to be of assistance. Let us know if you have any other questions!

DaBostonBeast said:

I can't believe the rep answered this and never mentioned that the 3400G is actually a 2000 series chip with graphics CU's. With the new 4700G it's a 3000 series chip. APU's on Ryzen just run a Generation behind. There is no reason it shouldn't work with a B450 Board unless something is broken. If you had updated the Bios you'd probably just be S.O.L. since it's a 1 way trip.

You are correct in that the Ryzen 3000 APU's are based on the Zen + architecture, not Zen 2, however they did still require a BIOS update as they were not compatible with the B450 chipset out of the box. Their specific microcode was not added to the ASUS Prime B450m until BIOS version 1201 (released 5/10/2019), which was the exact same BIOS that added support for the Zen 2 (3000 series) processors. https://www.asus.com/us/Motherboards/PRIME-B450M-A/HelpDesk_CPU/. 

The architecture of the processor was not relevant to the compatibility question as despite the older Zen+ architecture, it required the exact same BIOS as the rest of the 3000 series for compatibility. This is why OP asked about the sticker as it would designate that the board had the BIOS required to allow the processor to POST.

As for the 4700G, there was far less information about that processor over a month ago when this thread originally was posted as the 4700G just paper launched yesterday on AMD's website. As an enthusiast, I like to keep up on all upcoming hardware launches, but I also cannot provide advice based on unreleased products as they are subject to change prior to officially launching. Rest assured that we do not take misinformation lightly and would never deceive a customer with the information we give.