Building a dual cpu X79 socket R mainboard into a PC

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  • This topic has 5 replies, 3 voices, and was last updated Jan 6-9:52 pm by roland.
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  • #49184
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    roland

    Several dual cpu mainboards have appeared on the Chinese markets under the tag X79 using socket R or LGA2011 cpu format. There is a variant under the tag X99 which uses a somewhat different socket type cpu. This text describes what I did to make a dual cpu X79 mainboard into a working PC running antiX 19, hopefully at minimal cost. There are minor hardware variations within this family of X79 tagged mainboards, mainly concerning the number of memory slots per cpu 2 or 4) and the number of SATA ports (4 or 6), and the positions of certain components and power input sockets on the board.

    The board format is a variant of ATX a couple of inches or so wider than standard ATX but not so long as some, because the number of PCI-express expansion slots has been kept to 4, a practical minimum. This results that in the usual PC ATX case not all the screw holes on the right hand side will correspond to a threaded hole in the backsheet, although the holes to the left will all line up as intended. Some cases will not accept this board at all, the back sheet not being flat enough nor wide enough to take the board, or having a step or fold in the back sheet towards the right.

    I looked through my junk cases and found one with a flat back sheet, without folds or corrugations over the width and length of the board. However part of 3 of the 4 drive bays overlapped one corner of the board, masking certain power sockets and attachment points. I therefore with tinsnips clipped out the lower 2 bays completely where they overlapped the board, and half of the bay above, thus making enough room around the board for the screws, cables and components required. This left just 1 full length 5 1/4″ expansion bay for a DVD/RW and another half length bay for a short media device reader, but no bay for any hard drive.

    I screwed threaded brass 1/4″ board spacers into all the existing threaded holes in the back sheet, and attached the board to these, then marked through all the unused holes in the board onto the back sheet with an automatic centre-pop. Removing the board I drilled 2mm holes where marked, then crudely threaded them using a 4mm self-tapping screw, and screwed into these holes the required threaded brass 4mm spacers, with a drop of loctite to fix them. Some small holes in the board extremities only required a plastic spacer of the push-in type for support. Now I had the board securely attached with a full set of screwed and plastic spacers through the assigned holes.

    I made a 3 1/2″ hard drive tower to fix onto the floor at the front of the case, using 1/2″ x 1/8″ steel strip cut and welded into a rigid rectangular stack and drilled and countersunk to accept 5 drives. Modern hard drives are thinner than they once were, so the stack still provides adequate clearance for the right hand cpu cooling radiator. The base of the stack has threaded holes for fixing with machine screws from underneath the case.

    A tip to get all hard drive fixing holes in the right place is to carefully mark and double-check one strip for the drive fixing holes, drill 5mm through all 4 strips clamped together, countersink the holes if required by the screws you are using, then weld up the stack using cast-off hard drives screwed through these holes in 2 or 3 places, to obtain correct alignment of all the pieces and above all the drive fixing holes. I keep a set of terminally failed old heavy 3 1/2″ drives for just this purpose.

    I did not want 2 large fans roaring away continually. Besides that, some powered coolers will not physically fit into such a moderate size case anyway. I therefore used 2 passive cooling radiators attached to 2 steel mounting strips, as no mounting hardware came with the radiators, These strips were cut to shape as necessary to clear board components, then drilled, countersunk and threaded to attach to the mainboard cooler fixing holes, using 1/4″ spacers and countersunk 4×0.7mm screws, and tapped 4×0.7mm to receive the selected cooling radiators mounting screws. Some very careful marking and drilling was required at this stage. These radiators are large finned sheet metal assemblies and the memory slots are very close at top and bottom, but there is just clearance enough for DDR3 ECC REG memory with cooling sleeves. I decided on heavy copper 8mm thick heat sinks made from 40mm x 4mm solid copper strip, screwed together with conductive gel, then squeezed between these radiators and the cpu tops. The radiator fixing screws are lightly spring loaded to keep the heat sinks in place, assisted by a coat of conductive gel on all contact surfaces.

    To start with I used 2 matched very cheap Xeon 4-core cpus cast off from old servers running at 2400mhz, intending to move up to faster ones later, if appropriate. DDR3 Server ECC REG ram is required for these boards, I used 4 x 8gb dimm with cooling sleeves, again cast off from old servers. A 16-lane PCIe graphics card from my junk box, a new SATA-3 DVD/RW in the top bay, a new media device reader in the half length bay, a new PCIe Wlan and Bluetooth card, a new 6-port SATA expansion card and a new modular 750w power supply completed the components. The 4 hard drives, DVD/RW and Media device reader took up 7 SATA ports so I installed a 4-port SATA expansion card to bring the SATA2 and SATA3 combined total to 10.

    The modular power supply is almost a necessity as the case is now crowded with components, and this power unit permitted only the necessary looms to be present and to be most neatly routed. A bifurcated cpu power cable was also required as only one cpu 8-pin power cable came with the psu. 4 x 500gb 3.5″ new SATA-3 hard drives were fitted into the HD stack. Later I may put a 250gb solid disk in the spare hard drive bay as a boot disk.

    There is no onboard default graphics chipset but an onboard sound chipset is present, and there are 2xPCIe 16-lane slots and 2xPCIe 1 -lane slots, 2xSATA-3 and 4xSATA-2 ports and a PCIe-1 SATA expansion card provides 4 extra SATA-3 ports. There are 2 fast network ports and the associated chipsets onboard. USB 2.1 and USB 3.0 ports abound internally and externally. There are even the now mainly unwanted PS/2 keyboard and mouse ports.

    I installed a small case fan and also fitted a small fan arranged to blow through the hard drive stack, besides the power supply internal fan.

    A coat of paint inside and out before final assembly completed the hardware aspect of this project.

    The build fired up immediately and ran well allowing installation and updating of 19.2 in the first instance. Following installation antiX support advised that a different kernel was required as I experienced random freezing, so a fresh install of 19.3 with kernel 4.19.152 and using only Ceni to handle networking, has cured that trouble, and I am now setting things up as I prefer them. After a 2-hour run cpu temperature hovers around 48C-52C which sounds high but appears to cause no trouble – so far. This PC is not quite silent having 3 fans but is a much appreciated very quiet PC.

    It runs very fast, I have not done enough with it yet to appreciate quite fast, and my other old slow PCs make poor comparison material. But the usual bottlenecks of networking and plug-in external devices are still there to hold things up somewhat.

    I hope this build description will be of help to any antiX user wishing to build a similar PC, good luck to all experimenters!

    #49189
    Member
    roland
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    More build photos

    #49204
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    roland
    #49219
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    Brian Masinick
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    Wow! That’s quite a system Roland! That is one feat of hardware engineering, no doubt about it.
    With multiple fans, I imagine the total amount of heat that becomes exhaust is measurable.
    Will your unit, by any chance, also HEAT a small room? [grin]

    In any case, great exercise; I hope that you have a lot of satisfaction with it, the time spent, and hopefully it will provide you with plenty of learning, features, performance and fun. Thanks for sharing your skills and your most recent project with us!

    Brian Masinick

    #49235
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    skidoo
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    2 matched very cheap Xeon 4-core cpus

    I’m curious to know the exact CPU model you chose.

    FWIW, we have an X79 system here, but its processor is i7-3930K, not Xeon. Undervolted via bios, and frequency scaled to idle at 1.2GHz, its cooling fan is usually near-silent. I was quite surprised when I (Kill-a-watt) tested the system and discovered it draws only 72watts when idling, and around 115 during stress stesting. (Surprised, given the “TDP 130W” spec of the CPU alone.)

    #49236
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    roland
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    The cpus were a matched pair of Intel Xeon X5 2609 2.4ghz and they cost the huge sum of 9.20 euros including free postage from China !! In USD terms that is about 10 dollars. I bought such low spec cpus just to get the project off the ground without breaking the bank, and may well step up to a more powerful pair when I have more experience with this PC.

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