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AMD FX builds, GeForce GTX and PCIe 3.0

Patrick_Lindber
Level 7
Hi,

I am not personally building anything right now, but I'm still
interested to plan different kind of builds. I've been interested
in AMD platforms lately. Especially an AMD FX is very attractive
when making a little bit cheaper build still meant for gaming or
some heavier use.

But in many cases a GeForce GTX may still be the better choice
than a Radeon. These modern GeForces operate via PCIe 3.0 bus
(and also the Radeons). But I have noticed that there are not
many AMD motherboards that have any PCIe 3.0 slots. They have
only PCIe 2.0 or 1.0 slots.

I know that basically a PCIe 3.0 card works on a PCIe 2.0 slot, but
doesn't it limit the speeds that the card itself could work? :confused:
406 Views
3 REPLIES 3

NemesisChild
Level 12
You would be hard pressed to see any performance loss running on a PCIe 2.0 system.
Intel i9 10850K@ 5.3GHz
ASUS ROG Strix Z490-E
Corsair H115i Pro XT
G.Skill TridentZ@ 3600MHz CL14 2x16GB
EVGA RTX 3090 Ti FWT3 Ultra
OS: WD Black SN850 1TB NVMe M.2
Storage: WD Blue SN550 2TB NVMe M.2
EVGA SuperNova 1200 P2
ASUS ROG Strix Helios GX601

Korth
Level 14
Only the mightiest of today's newer graphic cards - 12GB Titan X, workstation cards, etc - can fully saturate x16 PCIe 2.0 bandwidth and thus gain any real benefit from PCIe 3.0. A multi-GPU through x8/x8 PCIe 2.0 usually splits bandwidth evenly enough that PCIe 3.0 still isn't a substantial upgrade - at least so long as a direct electrical GPU bridge is used instead of "bridgeless" links across the PCIe bus. 3-way multi-GPU under load can be throttled by x8/x4/x4 PCIe 2.0 in some games (it depends a lot on how they use GPU resources). Benchmarks can demonstrate the limits, but they don't always represent actual real-world performance. Many games are better optimized for AMD or for NVidia, some games will run noticeably better on one platform than on the other (and I think this is an important point when deciding on a platform meant to run some particular game you might have your heart set on.)

Some oddities have been noted where particular games run faster on PCIe 2.0 than PCIe 3.0, or run faster without HyperThreading, or whatever. Just quirky hardware/software combinations which seem to run unexpectedly well or unexpectedly awful together.

AMD motherboards rarely support SLI, it's an NVidia licensing thing. An AMD FX9590/RV990FX/SB950/DDR3 or an AMD A10-7870K/A88X/DDR3 platform running 2-GPU CrossFire can still impressive enough for "elite" gamers - and have a lower overall price tag.
"All opinions are not equal. Some are a very great deal more robust, sophisticated and well supported in logic and argument than others." - Douglas Adams

[/Korth]

Patrick_Lindber
Level 7
Ok, that was new. The answer was pretty exhaustive! Thank You! 😉