Question Getting really bad performance with RTX 4070 and Ryzen 7 5800x3d (new build)

[unclejiggy]

As the title states, I'm getting nowhere near the performance levels I should be: e.g. struggling to get above 40fps on Helldivers 2 on low settings, 20fps on Kingdom Come Deliverance on Low settings

Playing at 1440p
CPU: AMD Ryzen 7 5800x3d (New)
Motherboard: MSI B450 Gaming Plus AM4 (second hand)
Memory: 2x8gb Corsair Vengeance LPX DDR4-3200 (second hand) + 2x16gb Corsair Vengeance LPX DDR4-3000 (new) (already tried with just the dual 2x16gb ram)
Storage: ADATA XPG SX8200 Pro 1TB M.2 (new)
Video Card: RTX 4070 (new)
Case: Montech AIR 903 MAX (new)
Power Supply: MSI A650BN 650W Bronze (new)

3dmark results:

HWmonitor results in-game:

 

[Darkbreeze]

Update BIOS and update motherboard drivers especially chipset, audio and LAN/WiFi. Not with a "utility" including any of the godforsaken motherboard manufacturer's utilities, which, if you using Dragon center get rid of it, but directly downloaded from the product support page for your motherboard. And, do a clean install of your Nvidia drivers using the DDU. And, do a hard reset of your BIOS. You have a B450 board so I'm sure you've had this a while, long before you got that 5800x3d. So do all of that and if you don't see improvement, do a CLEAN install of Windows, which I'm equally sure you most likely did not do when you upgraded to the 5800x3d.

If you DID those things already, ALL of them, and saw no improvement, then I'd ask what CPU cooler are you running and what is your case cooling configuration looking like? Because your clocks in the screenshot do not seem to be in line with what they should be.