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  1. #1
    ROG Member Array Dresk PC Specs
    Dresk PC Specs
    MotherboardASUS Rampage VI Apex
    ProcessorIntel 7900x (8C/16T @ 4.8Ghz, -1AVX, -4AVX512)
    Memory (part number)F4-3200C14-8GTZSW
    Graphics Card #1NVIDIA TITAN RTX
    Sound Card(onboard)
    MonitorASUS ROG PG258Q
    Storage #1Samsung 970 Evo Plus 2TiB NVMe
    Storage #2Samsung 970 Evo Plus 2TiB NVMe
    CPU CoolerCustom Water Loop with Quad 140MM BlackIce Radiator and EK Blocks
    CaseCorsair OBSIDIAN 900D
    Power SupplyCorsair AX1600i
    Keyboard DECK PS/2 Keyboard
    Mouse Logitech G5
    OS Win7 64bit (gaming), Win10 64bit (work)

    Join Date
    Jul 2012
    Reputation
    10
    Posts
    6

    ROG X299 Boards - Disable AVX(1/2/512f) in BIOS

    Hey guys,

    A rather unorthodox set of questions / request here. I am still trying to use Intel HEDT CPUs as my gaming CPUs, due to the excellent chipsets (X299) and all the other bells and whistles that come with the HEDT platform.

    Unfortunately, starting with Skylake-X for me, it has just become an absolute pain to maintain the frequencies across all my cores, and with AVX instructions that sets everything back further. To be clear, I have a 7900x with 2 cores disabled and all cores running @ 4.8GHZ with -1 AVX and -4AVX512. I can deal with AVX at -1, but AVX512 for gaming, it's just a disaster - with these clockspeeds the CPU would want to gobble up 400W+.

    I'm also a programmer, so I would appreciate AVX512 when compiling (especially after seeing some benchmarks.) However, the bottom line is, as a GAMER, when running Windows 10, you never know when some background process is going to kick in AVX512 intrinsics, and that's going to ruin your benchmarks. Having an option in the BIOS similar to VT-X to disable the CPUID bits for AVX, or especially AVX512, would do wonders for people wanting to game on Skylake-X without the risk of AVX512 kicking in.

    I am aware of using bcdedit to disable XSAVE, though that's not a perfect solution. XSAVE is meant to optimize context switching, and goes beyond just AVX and AVX512 (it has some SSE it stores), plus again many of us are fine with AVX1/2 . The Linux kernel already supports full granularity of what XSAVE features to disable, meaning it can do just AVX1/2 and AVX512 ( https://lore.kernel.org/patchwork/patch/768884/ ).

    If anyone wants the mod the BIOS to trap these CPUID bits, I'll be happy to help and be a guinea pig. I really want to stay on HEDT, but if I'm staying with Intel (foregoing AMD for the moment), their desktop CPUs are becoming no-brainers for gaming performance.

    Thanks all, I will have a signature with my rig details up soon.
    - Dresk
    Last edited by Dresk; 09-01-2019 at 11:32 PM.
    • Motherboard : ASUS Rampage VI Apex
    • Processor : Intel 7900x (2 cores disabled, 8C/16T @ 4.8Ghz, -1AVX, -4AVX512)
    • Grapics Card : NVIDIA TITAN RTX
    • Cooling : Custom Waterloop w/BlackIce Quad 140mm GTX Radiator and Swiftech Dual MCP35X2 Pump
    • Memory : (4) G.Skill DDR4-3200 @ 14-14-14-32
    • PSU : Corsair AX1600i
    • Case : Corsair OBSIDIAN 900D
    • Monitor : ASUS ROG PG258Q
    • Drive : (2) Samsung 970 Evo Plus 2TiB NVMe
    • OS's: Win7 64bit Gaming; Win10 64bit Working

  2. #2
    ROG Guru: Orange Belt Array ThrashZone PC Specs
    ThrashZone PC Specs
    MotherboardASUS x99 sabertooth & x299 Rampage VI Apex
    Processori7-5930k & i9-9940x
    Memory (part number)Trident-Z 3200C14 & Trident-Z 3600C16 both Samsung B-Dies
    Graphics Card #1EVGA 1080ti FTW3 water block & Titan Xp copper water block
    MonitorAOC G2460PG 24"G-Sync 144Hz & ASUS VG248QE 24" 144Hz
    Storage #12-Samsung 970 Evo Plus 500gb M.2 & 2.5" ssd's 850 pro's for os 850 evo for games
    Storage #22-LG Blu-Ray WH16NS40
    CPU Coolerx99 2-240GTX with Heatkiller-4-Pro/ vrm water block Both&x299 2-280GTX 2-D5's before and after rads
    Case2- Corsair 450D with second floors for 240GTX & 280GTX rads enclosed and filtered on top
    Power SupplyEVGA 1000P2 & EVGA 1200P2
    Keyboard Logitech G910 Orion Spectrum & Logitech G710+
    Mouse 2-Red dragon Perdition
    OS Win-7 & win-10 pro on both systems Win-7 everyday os
    Accessory #1 Heatkiller IV Pro plexi/ Copper base on both systems
    Accessory #2 Mayhems Biocide and Inhibitor with distilled water
    Accessory #3 Mayhems 3/8-5/8" clear soft tubing
    ThrashZone's Avatar
    Join Date
    Oct 2017
    Reputation
    13
    Posts
    305

    Hi,
    I don't see why you or anyone would think running 4.8 on avx offset 1 and think avx 512 offset at 5 is the problem gaming

    Obviously 4.8 is not stable and would usually need a offset of 3 to drop to 4.5 from 4.8. once that happens 4.8 is pointless us 4.7 or like I said a probably more stable 4.5 all core where neither avx is is needed and can be set to auto.

    Also not sure why you disable 2 cores but could mean the chip is not that good "pigeon poop still Inside" so you disable the two worst cores.

    Really funny part is complaining that at you're clocks and gpu how much voltage is used

  3. #3
    ROG Member Array Dresk PC Specs
    Dresk PC Specs
    MotherboardASUS Rampage VI Apex
    ProcessorIntel 7900x (8C/16T @ 4.8Ghz, -1AVX, -4AVX512)
    Memory (part number)F4-3200C14-8GTZSW
    Graphics Card #1NVIDIA TITAN RTX
    Sound Card(onboard)
    MonitorASUS ROG PG258Q
    Storage #1Samsung 970 Evo Plus 2TiB NVMe
    Storage #2Samsung 970 Evo Plus 2TiB NVMe
    CPU CoolerCustom Water Loop with Quad 140MM BlackIce Radiator and EK Blocks
    CaseCorsair OBSIDIAN 900D
    Power SupplyCorsair AX1600i
    Keyboard DECK PS/2 Keyboard
    Mouse Logitech G5
    OS Win7 64bit (gaming), Win10 64bit (work)

    Join Date
    Jul 2012
    Reputation
    10
    Posts
    6

    ThrashZone,

    My system is 100% stable with 8C @ 4.8Ghz on all cores. I'm obviously trying to get the most single-threaded performance I can get out of my rig. The reason I disabled 2 cores is because, literally, stressing my CPU as much as I could with 10C at 4.8 used over 400W on the CPU. Dropping the frequency to 4.7 meant no difference, and I couldn't adjust VCore at all.

    I don't need 10 cores. I do like the PCI-E lanes and cache I get with this CPU. By disabling 2 cores and setting frequency to 4.8 with AVX1/2 at -1 and AVX512 at -3, the system is 100% stable.

    My question was a very simple question : can we, via the BIOS / UEFI, disable the CPUID bits that report support of AVX512? No gamer needs AVX512 and we already know Windows 10 can at times trigger AVX512 instructions doing ordinary background tasks, making our cores and gaming performance dip vastly (just look at people benchmarking Windows 10 and noting the possibility of AVX1/2 or AVX512 kicking in during a game benchmark.

    Please, I ask that this thread not be derailed. I know I have an RTX Titan, but most D3D11 titles are limited by single-threaded performance, so I want to keep that high, across ALL cores. I'm not using Intel Turboboost 3.0 because Windows 7 doesn't support it and, when I'm booted into Windows 10, I still do not want to use it. The only reason I'm sticking to HEDT is for the PCI-E lanes, wonderful motherboards and, as a programmer who uses Intel's software to diagnose cache line performance / hits / etc for optimum performance, I know how much cache can help performance.

    Thank you.
    • Motherboard : ASUS Rampage VI Apex
    • Processor : Intel 7900x (2 cores disabled, 8C/16T @ 4.8Ghz, -1AVX, -4AVX512)
    • Grapics Card : NVIDIA TITAN RTX
    • Cooling : Custom Waterloop w/BlackIce Quad 140mm GTX Radiator and Swiftech Dual MCP35X2 Pump
    • Memory : (4) G.Skill DDR4-3200 @ 14-14-14-32
    • PSU : Corsair AX1600i
    • Case : Corsair OBSIDIAN 900D
    • Monitor : ASUS ROG PG258Q
    • Drive : (2) Samsung 970 Evo Plus 2TiB NVMe
    • OS's: Win7 64bit Gaming; Win10 64bit Working

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