- last edited on by
ROGBot
A little bit ago, I put together a configuration for a C612 µATX board: Will there be Rampage V Formula, Gene and Impact ?. Another forum member asked if I could put together an ROG version of the board. I thought about it and really couldn't think of how adding any of the usual "fan boy" features ROG adds would improve the board, especially for one based on a C612 chipset. A lot of those additional features are usually degrading for the absolute performance; however, some of the recent remarks alluded to about the performance of the Maximus VII Impact on Anandtech, such as DPC latency, show there have been improvements. I'm still not a fan of splitting off half of the PCI-e 3.0 to support an M.2 slot, especially with High Bandwidth Memory (aka HBM) on GPUs right around the corner, shifting the GPU performance bottleneck back onto the PCI-e interface (this notion is further reinforced by NVIDIA developing NVLink). The simple fact of the matter is that PCI-e through-put and latency will be the limiting factor, once again, and splitting up the lanes to support multiple GPUs or other peripherals will substantially adversely affect performance (multiple GPUs will not scale anywhere close to how well they do currently).
So, with that in mind, my attention turned to what a motherboard for Skylake could look like. With non-Extreme processors you only have 20 PCI-e lanes (16 PCI-e 3.0 and 4 PCI-e 2.0 that are usually used for the DMI 2.0 connection to the chipset). While we do not know publicly what Skylake will offer, I'll guess that it will either be the exact same or DMI will be upgraded to 3.0 and all 20 PCI-e lanes will meet the 3.0 standard. This points to a Mini-ITX or µATX board being the ideal form-factors as additional PCI-e slots of a full ATX board will not significantly improve performance, as previously noted. I have a strong preference for 'elegant' design and engineering, so I'm partial to the Mini-ITX form-factor and that is where my thoughts lead me.
So for my train of thought here: one of the things that Mini-ITX boards are missing compared to all the other form factors are the second DIMM slots for the memory channels. I've noticed MSI has probably the best lay-out for a Mini-ITX motherboard out there currently, and if you were to move the socket over a little bit, you could possibly add in the two additional slots (connected up in a T-topology). This however will start to crowd the power circuitry on the ROG Impact boards normal location, so I swiveled it over )not unlike where MSI has their power circuitry). This also provided a nice open area for air flow, so there is now both the top and side open to air flow, helping that situation. With the power circuitry shifted over, there is no room for the mPCIe combo card, nor the audio solution currently used. I took the stand-off mezz card concept that I used with the µATX for the audio and barely fit, but could work here. I kept the other daughter cards from the Maximus VII Impact along with the TPM slot between them, as they were fairly efficient in their implimentation. The USB ports are now of the Type-C variety, as I expect many devices will start to move over to that interface in the next year or two. Whether USB 3.1 is added to the chipset for Skylake has yet to be seen (I can't wait for chipsets to be killed off and all circuitry be integrated into the CPU...mobile is pushing, just needs to get there). There are two M.2 slots, both with x4 electrical connectivity back to the chipset. The shorter slot would probably be used for wireless, handling 802.11ad 60GHz data rates, while the longer would be for storage or expansion cards. up to 80mm. 6 SATA ports, USB headers, standard I/O stuff... I located the I/O and expansion to keep the airflow as open as possible on the one side; I know that means some traces will need to go across the board from the PCH (compromise).
I did create an alternate configuration. This would replace the chipset with a PLX switch, either a PEX 8748 for PCI-e 3.0 or PEX 8648 for PCI-e 2.0, interfacing with the PCI-e lanes normally used for DMI. This would then be configured so that there would be 12 x4 PCI-e lanes coming off of it. One would obviously connect to the processor. The others would be for: Ethernet, wireless M.2 slot, audio, 2-4 USB 3.1 controllers (I don't know what the USB 3.1 header will look like; the protocol has reduced overhead, higher signalling frequencies, and additional pins for future growth, so I just put in the USB 3.0 header as a surrogate), 3-5 additonal M.2 slots (several will have to go on the back of the board, similar to the Z97I-Plus; this will probably mean higher quality vias, blind or back-drilled, will need to be used). This removes the shackles of the chipset I/O and allows for the motherboard manufacturer to change it up at their will. To accommodate legacy I/O, the long M.2 slot could have a media controller or two with SATA and USB headers on it.
So yeah, just some of my thoughts on what ASUS could do for Skylake. Feel free to pick it apart, I don't get easily offended. Cheers!
So, with that in mind, my attention turned to what a motherboard for Skylake could look like. With non-Extreme processors you only have 20 PCI-e lanes (16 PCI-e 3.0 and 4 PCI-e 2.0 that are usually used for the DMI 2.0 connection to the chipset). While we do not know publicly what Skylake will offer, I'll guess that it will either be the exact same or DMI will be upgraded to 3.0 and all 20 PCI-e lanes will meet the 3.0 standard. This points to a Mini-ITX or µATX board being the ideal form-factors as additional PCI-e slots of a full ATX board will not significantly improve performance, as previously noted. I have a strong preference for 'elegant' design and engineering, so I'm partial to the Mini-ITX form-factor and that is where my thoughts lead me.
So for my train of thought here: one of the things that Mini-ITX boards are missing compared to all the other form factors are the second DIMM slots for the memory channels. I've noticed MSI has probably the best lay-out for a Mini-ITX motherboard out there currently, and if you were to move the socket over a little bit, you could possibly add in the two additional slots (connected up in a T-topology). This however will start to crowd the power circuitry on the ROG Impact boards normal location, so I swiveled it over )not unlike where MSI has their power circuitry). This also provided a nice open area for air flow, so there is now both the top and side open to air flow, helping that situation. With the power circuitry shifted over, there is no room for the mPCIe combo card, nor the audio solution currently used. I took the stand-off mezz card concept that I used with the µATX for the audio and barely fit, but could work here. I kept the other daughter cards from the Maximus VII Impact along with the TPM slot between them, as they were fairly efficient in their implimentation. The USB ports are now of the Type-C variety, as I expect many devices will start to move over to that interface in the next year or two. Whether USB 3.1 is added to the chipset for Skylake has yet to be seen (I can't wait for chipsets to be killed off and all circuitry be integrated into the CPU...mobile is pushing, just needs to get there). There are two M.2 slots, both with x4 electrical connectivity back to the chipset. The shorter slot would probably be used for wireless, handling 802.11ad 60GHz data rates, while the longer would be for storage or expansion cards. up to 80mm. 6 SATA ports, USB headers, standard I/O stuff... I located the I/O and expansion to keep the airflow as open as possible on the one side; I know that means some traces will need to go across the board from the PCH (compromise).
I did create an alternate configuration. This would replace the chipset with a PLX switch, either a PEX 8748 for PCI-e 3.0 or PEX 8648 for PCI-e 2.0, interfacing with the PCI-e lanes normally used for DMI. This would then be configured so that there would be 12 x4 PCI-e lanes coming off of it. One would obviously connect to the processor. The others would be for: Ethernet, wireless M.2 slot, audio, 2-4 USB 3.1 controllers (I don't know what the USB 3.1 header will look like; the protocol has reduced overhead, higher signalling frequencies, and additional pins for future growth, so I just put in the USB 3.0 header as a surrogate), 3-5 additonal M.2 slots (several will have to go on the back of the board, similar to the Z97I-Plus; this will probably mean higher quality vias, blind or back-drilled, will need to be used). This removes the shackles of the chipset I/O and allows for the motherboard manufacturer to change it up at their will. To accommodate legacy I/O, the long M.2 slot could have a media controller or two with SATA and USB headers on it.
So yeah, just some of my thoughts on what ASUS could do for Skylake. Feel free to pick it apart, I don't get easily offended. Cheers!
