define "older configurations". There is a good chance there are no drivers for older systems. Also what SSDs do you mean exactly? some examples would help, as there are a number of different ways PCIe SSDs have been made.

Koltoroc wrote:

define "older configurations". There is a good chance there are no drivers for older systems. Also what SSDs do you mean exactly? some examples would help, as there are a number of different ways PCIe SSDs have been made.

Sorry. I am running modern linux kernels/distribution so I imagine drivers would not be a problem. I was thinking how fast SSD PCIex would be on a dual core configs like Athlon64 X2 / Core 2 cpu, comparing to the usual cheap SSD SATA3 on SATA2 mobo, disk.

If the SATA3 SSD is limited to SATA2 speeds, the difference should be significant. direct PCIe has measurable, but not necessarily notable latency and seek time improvements (most of the gains here are from moving from mechanical to SSD in the first place, further improvements are not that significant). Transfer speeds will be significantly better, but how much depends on number of lanes, which gen the lanes are and which gen the SSD supports, and what limits are there from the controller and flash chips, but also ho large the SSD is (larger normally means more parallel access since there are more flash chips). I would expect a minimum of 4-5x the transfer speed if you have a good ssd. Another big advantage are massively increased parallel input/output operations. SATA3 tops out at around 75k, PCIe SSDs can reach over 500k while writing and over 900k while reading (though those will be prohibitively expensive, 100-300k is more likely in the affordable range). IOPS are not that relevant for desktops, but datacenters and large databases that don't fit in memory can massively profit from that.

To which degree an old dualcore can realize these improvements, I don't know, I'm not sure anyone ever bothered to test that.

There is another important aspect, You can't boot from them, at least not directly. Bios/UEFI support for booting from PCIe/NVme SSDs is rather recent, I believe the first intel chipsets supporting that were released around the HAswell CPU generation, while AMD only supports it (with a few rumored exceptions) since Ryzen. I believe you can setup linux to chainboot from and PCIe SSD, but I'm not certain. You would still need an addition device for the bootloader at least. Windows won't be able to boot from a PCIe SSD without bios support at all IIRC.

Koltoroc wrote:

If the SATA3 SSD is limited to SATA2 speeds, the difference should be significant. direct PCIe has measurable, but not necessarily notable latency and seek time improvements (most of the gains here are from moving from mechanical to SSD in the first place, further improvements are not that significant). Transfer speeds will be significantly better, but how much depends on number of lanes, which gen the lanes are and which gen the SSD supports, and what limits are there from the controller and flash chips, but also ho large the SSD is (larger normally means more parallel access since there are more flash chips). I would expect a minimum of 4-5x the transfer speed if you have a good ssd. Another big advantage are massively increased parallel input/output operations. SATA3 tops out at around 75k, PCIe SSDs can reach over 500k while writing and over 900k while reading (though those will be prohibitively expensive, 100-300k is more likely in the affordable range). IOPS are not that relevant for desktops, but datacenters and large databases that don't fit in memory can massively profit from that.

To which degree an old dualcore can realize these improvements, I don't know, I'm not sure anyone ever bothered to test that.

There is another important aspect, You can't boot from them, at least not directly. Bios/UEFI support for booting from PCIe/NVme SSDs is rather recent, I believe the first intel chipsets supporting that were released around the HAswell CPU generation, while AMD only supports it (with a few rumored exceptions) since Ryzen. I believe you can setup linux to chainboot from and PCIe SSD, but I'm not certain. You would still need an addition device for the bootloader at least. Windows won't be able to boot from a PCIe SSD without bios support at all IIRC.

Interesting, thank you. I didn't know about the boot problems on older pc. Maybe the usual SSD on SATA beside being slower have enough benefits for the old computers.