Just checking if my interpretation of the block diagram is correct on GA-H55-USB3 with regards to how Gigabyte have allocated the H55 PCIe lanes and the interesting NEC USB 3 controller.
(r1.0, diagram is literally the same for r2.0, though they used a different RTL PCIe controller)
First up, i believe the H55 has six PCIe 1.1 lanes. From the above I see:
3 lanes dedicated as PCIe x1 slots,
1 lane dedicated as Gigabyte/Jmicron SATA2 chip
1 lane dedicated for Gigabit lan
1 lane dedicated to the switch which in turn goes to the NEC D720200F1 USB 3.0 controller
I noticed the Gen 2 link from the switch which ties in to the PCIe x16 from the CPU.
From what I looked up, Gen 1 (PCIe 1.x) is about 250MB/sec data rate per lane (& per direction), less once you take into account protocol overheads. Gen 2 (PCIe 2.x) is about 500MB/sec with the same caveat.
At a guess, if there is a discrete graphics card installed, does the switch use the (Gen1/PCIe 1.x) x1 lane?
If onboard video is used, does it use the (Gen2/PCIe 2.x) x1 lane?
So basically, for onboard video setups, you have plenty of bandwidth for the USB 3 controller. Whack in a video card, and it will fall back to the PCIe 1.1 x1 lane which is still damn fast at this stage, but technically somewhat bandwidth-limited?
Thanks
(r1.0, diagram is literally the same for r2.0, though they used a different RTL PCIe controller)
First up, i believe the H55 has six PCIe 1.1 lanes. From the above I see:
3 lanes dedicated as PCIe x1 slots,
1 lane dedicated as Gigabyte/Jmicron SATA2 chip
1 lane dedicated for Gigabit lan
1 lane dedicated to the switch which in turn goes to the NEC D720200F1 USB 3.0 controller
I noticed the Gen 2 link from the switch which ties in to the PCIe x16 from the CPU.
From what I looked up, Gen 1 (PCIe 1.x) is about 250MB/sec data rate per lane (& per direction), less once you take into account protocol overheads. Gen 2 (PCIe 2.x) is about 500MB/sec with the same caveat.
At a guess, if there is a discrete graphics card installed, does the switch use the (Gen1/PCIe 1.x) x1 lane?
If onboard video is used, does it use the (Gen2/PCIe 2.x) x1 lane?
So basically, for onboard video setups, you have plenty of bandwidth for the USB 3 controller. Whack in a video card, and it will fall back to the PCIe 1.1 x1 lane which is still damn fast at this stage, but technically somewhat bandwidth-limited?
Thanks
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