PCI-E 4.0 GPU in PCI-E 2.0 slot?

[Game-Editor 2]

Hello. I have a GIGABYTE GA-78LMT-USB3 6.0 motherboard with a PCI-E 2.0 slot and I'm in need of a new GPU since my current AMD HD 7950 is malfunctioning. I've decided to buy an AMD RX 6600 which is PCI-E 4.0 and would like to know if it would work fine in a PCI-E 2.0 slot. I know PCI-E should be forwards and backwards compatible but I'm asking just in case.
How much performance would be lost?
Also do you have any thoughts specificaly on the Sapphire Pulse RX 6600?

[BiotechBen]

11 minutes ago, Game-Editor 2 said:

Hello. I have a GIGABYTE GA-78LMT-USB3 6.0 motherboard with a PCI-E 2.0 slot and I'm in need of a new GPU since my current AMD HD 7950 is malfunctioning. I've decided to buy an AMD RX 6600 which is PCI-E 4.0 and would like to know if it would work fine in a PCI-E 2.0 slot. I know PCI-E should be forwards and backwards compatible but I'm asking just in case.
How much performance would be lost?
Also do you have any thoughts specificaly on the Sapphire Pulse RX 6600?

You are gonna be running at pcie 2.0 x8, it's not ideal, and you'll be leaving performance on the table. How much: well that also depends on what CPU you have.

[mariushm]

PCI-E 2.0 runs at 500 MB/s per lane,  pci-e 3.0 runs at max 985 MB/s , pci-e 4.0 runs at around 1.9 GB/s

 

The RX 6600 can use maximum 8 pci-e lanes, so almost 16 GB/s which can be achieved using 16 pci-e 3.0 lanes or 32 pci-e 2.0 lanes.

The first slot on your motherboard should have 16 pci-e 2.0 lanes, but the RX6600 is designed to use maximum 8 no matter the slot, so the maximum transfer speed will be limited to a quarter of the maximum it could get (4 GB/s max)

Depending on the CPU you'll have and the amount of RAM, it can be enough to run games well at 1080 medium-high quality. A lot of CPUs that run on that motherboard will actually choke (limit) the video card performance, simply because the performance of each core is too low and the video card driver can't talk fast enough with the video card to keep the card fed with information.

[apoKhallipsa]

I had on Asus pcie 2.0 TX 5600 xt and it run kinda good but cpu hold it back 

[Game-Editor 2]

Thanks for the answers so far! My PC is running an AMD FX-8350 CPU and 2x8GB DDR3 RAM.
Seems like all of you agree that the GPU would be held back by the CPU. In that case what are your thoughts on the 6500 XT, would that be a good match? I have a decent aftermarket cooler on the CPU so I'll be able to overclock it if needed, but preferably not.

[RONOTHAN##]

2 minutes ago, Game-Editor 2 said:

In that case what are your thoughts on the 6500 XT,

That card is limited to x4 PCIe, an would do a lot worse. Realistically, the best option would be to spend the money you would spend on the 6600 on a used GTX 1080/RTX 2060 and a 12100F system, that should end up being roughly the same price overall as that card but would be much better performance in everything. 

[Game-Editor 2]

Alright I think I found the best option, GTX 1650.

It runs on x16, found it at a very good price, performs better than my current HD7950 and shouldn't be bottlenecked as much as the GPUs I mentioned previously. Also since it's a lot more efficient than my current GPU I'll have room for overclocking my CPU if needed. Thoughts?

 

One concern I have is that the 1650 isn't powered externally by 6/8 pin cables but directly from the PCI-E slot. So my question is can the PCI-E 2.0 slot on my motherboard deliver enough power to the PCI-E 3.0 GTX 1650?

[mariushm]

It won't be a good choice.

 

Really you shouldn't worry that much about video card being limited by the other hardware. It's not like the video card goes bad or suffers or gets stuck at that lower performance level if you use it with hardware that limits it - as soon as you upgrade the other stuff, the video card will run better.

 

Honestly, even right now, your FX-8350 is actually a bit limited by your choice of motherboard - you would probably gain 1% or more by using a motherboard with a proper AM3+ chipset and better VRM but would it be worth now to change just the motherboard? No.

 

The GTX1650 runs on pci-e x16 but doesn't even NEED the 16 pci-e lanes, because it's not powerful enough or fast enough that you would get high framerates, or that you would get the opportunity to run games at quality levels that would saturate the 4 GB of vram on the video card.

 

I'd suggest getting a video card with the idea that you'd use it for at least 5 years ... in a few years we'll have A LOT of games that won't even run on video cards with only 4 GB of memory onboard.

 

edit :  all pci-e slots can provide the same amount of power no matter the version, so it would be fine.

[jaslion]

Just get the rx6600 and cranck the settings then later upgrade your platform.

 

A gtx 1650 is just striaght up bad value a 6600 is a little more and even at 2.0 x8 will de better