Thursday, January 18th 2024
AMD's Phoenix 1 and Phoenix 2 APUs Differ in PCIe Lane Count, Affects NVMe Drive Performance and GPU PCIe Lane Count
At CES, AMD didn't give away too many technical details of its upcoming Ryzen 8000G-series APUs, but details are starting to trickle out and it's not all good news. As has been known for some time, AMD is using two different chips to make the Ryzen 8000G APUs and they're known as the Phoenix 1 and Phoenix 2, where the Phoenix 2 parts feature Zen 4c cores, which are not present in the Phoenix 1 APUs. This in and of itself shouldn't be a huge issue, although the Zen 4c CPU cores can be slightly slower in some tasks based on testing of AMD's EPYC server parts.
However, PCGamesN noticed that Gigabyte has posted the full specs for the B650E Aorus Elite X AX Ice motherboard and it looks like there's a much bigger difference between the Phoenix 1 and Phoenix 2 based APUs. Namely, the Phoenix 2 APUs have fewer PCIe lanes and as such are limited to two PCIe 4.0 lanes for the secondary NVMe slot. As if this wasn't bad enough, the Phoenix 2 APUs only have four PCIe 4.0 lanes for add-in GPUs, whereas the Phoenix 1 APUs have eight. This is very likely to lead to reduced performance if a higher-end GPU is used with such an APU. Note that this will vary depending on the motherboard design, but many B650/B650E boards feature a similar design with regards to the PCIe lanes coming from the CPU socket. Luckily, it's easy to avoid this issue, as the Ryzen 5 8600G and the Ryzen 7 8700G are both Phoenix 1 designs, whereas the Ryzen 5 8500G is the only Phoenix 2 design available in retail, as the Ryzen 3 8300G is an OEM only part.
Sources:
Gigabyte, via PCGamesN
However, PCGamesN noticed that Gigabyte has posted the full specs for the B650E Aorus Elite X AX Ice motherboard and it looks like there's a much bigger difference between the Phoenix 1 and Phoenix 2 based APUs. Namely, the Phoenix 2 APUs have fewer PCIe lanes and as such are limited to two PCIe 4.0 lanes for the secondary NVMe slot. As if this wasn't bad enough, the Phoenix 2 APUs only have four PCIe 4.0 lanes for add-in GPUs, whereas the Phoenix 1 APUs have eight. This is very likely to lead to reduced performance if a higher-end GPU is used with such an APU. Note that this will vary depending on the motherboard design, but many B650/B650E boards feature a similar design with regards to the PCIe lanes coming from the CPU socket. Luckily, it's easy to avoid this issue, as the Ryzen 5 8600G and the Ryzen 7 8700G are both Phoenix 1 designs, whereas the Ryzen 5 8500G is the only Phoenix 2 design available in retail, as the Ryzen 3 8300G is an OEM only part.
20 Comments on AMD's Phoenix 1 and Phoenix 2 APUs Differ in PCIe Lane Count, Affects NVMe Drive Performance and GPU PCIe Lane Count
Also this is a braindead move to get zen4 desktop chips on 8xxx numbering scheme, I couldn't give 2 effs about OEM's but they should've maintained the relatively good status quo like they did with zen3 :shadedshu:
Phoenix2 has 14 Gen4 lanes with 10 being usable on AM5 (4 lanes went to the chipset). In theory the board can do an x8 slot and a x2 nvme m.2.
But since the board are releaseds with the 24+4 lanes Raphael in mind, many board have an 2nd pcie x4 / nvme slot wired into the cpu.
So they either ditch those and risk customers complaing why certain slots don't work. Or they do this janky thing where every slot ended up gimped.
Nobody should use any Phoenix where a 7500F upwards paired with a dGPU is of more desire, obviously.
And with $176 SEP the 8500G seems not cheaper than the mentioned Raphael 7500F.
- Intel released 300 on salvaged dies that did not qualify for other i3 CPUs. Even 50 Gen5 lanes would not make it any better. Its connectivity is a total overkill for the CPU itself
- no one in their right mind would ever buy 300 CPU and pair it with speedy and expensive NVMe drives or GPUs. So, yes, it has more lanes, but no one really cares.
- let's clarify: Phoenix 2 is not a new chip. It has been around as 7440U and 7540U for entry school laptops and we knew last year already its spec with 10+4 PCIe lanes.
- now, Phoenix 2 is 8440U, 8540U, 8500G and 8300G
- Phoenix 2 is compact, very cheap to produce, with high yields, it has better iGPU than Intel 300 and enough connectivity for entry systems, ideally with A620 boards
- when paired with better B650 or X670 boards, Phoenix 2 chip will look like gimped APU due to board design decisions for more capable CPUs/APUs.
- it's up to motherboard vendor to expose what a SKU has to offer and Gigabyte did not maximize APU's connectivity here, to remain more compatible with other CPUs/APUs
- so, all your complaints to Gigabyte, please, and not to AMD
Gigabyte could have exposed more connectivity baked into APU + what is on B650 chipset:
- two USB4 ports, each at 40 Gbps - Intel 300, on the other hand, does not have integrated Thunderbolt 4
- DP 2.1 and HDMI 2.1 FRL ports for monitors - Intel 300 has older video standards in UHD710 graphics
- reconfigure PCIe 4.0 as x8 for GPU instead of offering two x4 (this was a trade-off in order for the board to be compatible with other CPUs/APUs)
- on the chipset, Gigabyte could have wired WiFi, LAN and two SATA ports on one PCIe x4 PHY, which would enable another Gen4 SSD (again, trade-off)
- personally, I'd never pair 8500G/8300G with such expensive ATX B650 board. Why would anyone do this? They can, and it will work, but it's pointless.
- 8600G, 8700G and other CPUs make much better match
- 8500G and 8300G are more suitable for A620 chipsets and entry B650 ITX boards in small factor entry systems. Pretty simple stuff. AMD hopes that DIY buyers can make reasonable matches of APUs and boards. And what is it that they "took away" on Phoenix 2 chip?
Have a look how packed Phoenix 2 chip is with 137 mm2 size.
X470 GAMING PLUS MAX | Motherboard | MSI Global
Intel is selling hybrid CPUs with now 3 types of different cores. But, yeah, let's talk about the possibility of someone buying an 8500G to use it with an RTX 4090 and two hi end PCIe 4.0 NVMe SSDs instead.
I mean, obviously someone will buy an APU to use with a hi end GPU. Right?
Agreed on the 4 CU IGP being problematic despite being double that of regular Zen 4 desktop parts.