Intel versus AMD - PCIe lane mix-up Confusion about lanes is common in modern hardware.
Intel versus AMD - PCIe lane mix-up Confusion about lanes is common in modern hardware.
What amount of information do you anticipate it will retrieve? Since it’s only gathering minor amounts, it won’t generate significant impact on other systems.
Edited December 19, 2019 by Mira Yurizaki
Hi, according to lto.org an LTO 8 drive can handle up to 750MB per second. I won’t choose that capacity since I don’t require it; likely LTO 6 would offer slower speeds. This is well beyond the performance of a spinning hard drive in my setup for video work, especially with large files—let alone 4K. Wikipedia mentions PCIe version 3 offers around 7.88 GB/s at double speed, dropping to half again at four times and one at one time. These numbers seem close to maximum, so background processes should slow things down. Currently there are no PCIe v4 SAS cards available, and even if they existed, my spinning drives wouldn’t keep up. I think the decision comes down to how long I need a full backup. It would be helpful to back up one drive while working on another, though I’m unsure if that’s feasible. If not, running backups at night might be the way. I’m wondering if PCIe lanes are only used when data is being transferred—they aren’t locked out by cards requesting exclusive access. That means having a graphics card run slower during backups shouldn’t cause problems, but I’m puzzled about how lane allocation works. What I’ve read suggests 16 lanes are reserved for the graphics card on x570, and I don’t know how the system moves 8 of them on an x470. Is it dynamic? Does it need a reboot?
The card locks its lanes from the start, which isn't flexible. However, real traffic changes, and you should consider actual bandwidth usage rather than fixed lanes. If all your storage connects directly to the chipset, the main constraint is CPU-chipset speed—potentially up to 4GB/s. When LTO reaches its limit, like 500MB/s (or 1GB/s if doubled), you still have about 3GB/s available, meaning it's far from being full. If your LTO relies on a spinning drive, it won't exceed 100-200MB/s, so the situation remains manageable.
PCI 2.0 lanes deliver about 500 MB/s each. PCI 3.0 lanes provide roughly 970 MB/s per lane. These are the upper limits; real performance is lower due to overhead from headers and framing. You'll typically see around 490 MB/s for PCIe 2.0 lanes and approximately 950 MB/s for PCIe 3.0. The connector design separates the physical slot from the actual lane count—so a slot labeled PCIe x16 might be longer but only hold four lanes. Any device connected must support communication with the system using just one lane, as required by the standard. If you wish, you can adapt a PCIe x4 or x8 card into a PCIe x1 slot using a riser cable, though speeds will drop significantly—possibly to about 900 MB/s. Some chipsets include firmware checks that block operation if fewer than the needed lanes are available, such as certain raw capture cards needing at least one lane for HD data. A LTO8 drive can reach up to 750 MB/s, but this depends on compression; uncompressed files will match the drive's theoretical rate. Most media files won't compress, so actual speeds align with tape transfer rates. You'll generally connect your card directly to a PCIe slot that matches its lane count, whether it's x1, x8, or x16. Video cards and chipsets are designed to work within these constraints, using the processor's dedicated channel for data flow. Motherboards with separate lanes (like B450) allow flexibility—placing a card in a lower lane slot frees up higher lanes for other devices. The chipset manages communication between the CPU and memory, while the PCIe lanes handle data transfer. If you need more lanes, some boards can reroute unused slots, but this is uncommon.
Hi, thank you for your message. The information you shared about LTO 8 speed and compression is helpful. It seems the actual performance might be reduced due to compression, which could affect transfer speeds. Regarding motherboards, there are many options available. I’m looking for a resource that lets you compare features directly rather than choosing based on predefined lists. Any recommendations would be greatly appreciated.