8.0 KiB
Mixed memory on idols-ai
128G from JUHOR 2×48G + GLOWY 2×16G. All four DIMMs are needed because 96G is insufficient.
Current configuration
CPU VDD2 is set to 1.17 V (BIOS reads 1.168 V). This is the best configuration tested so far, but it still froze during daily use on 2026-10-11. Keep it for normal use for now; higher tested VDD2 settings have not provided a stable alternative.
| Field | Setting |
|---|---|
| XMP | Disabled |
| Gear mode | Gear2 |
| Memory speed | 4800 MT/s |
| CPU VDD2 | 1.17 V fixed (BIOS reads 1.168 V) |
| VCCSA | Auto (BIOS reads 1.288 V) |
| VDD2_MV (BIOS label) | Auto (BIOS reads 1.280 V) |
| DRAM VDD | 1.28 V fixed |
| DRAM VDDQ | 1.28 V fixed |
| DRAM VPP | Auto (1.8 V) |
| tCL / tRCD / tRP / tRAS | 40 / 40 / 40 / 77 (last photographed values) |
Voltage settings and readings come from BIOS and user reports, not OS measurements.
Hardware
- CPU: Intel Core Ultra 7 270K Plus.
- Board: Colorful CVN Z890 ARK FROZEN V20, BIOS 1013.
- Each channel: 48G (2R) in DIMM0, 16G (1R) in DIMM1.
- The 16G pair was added on 2026-10-06.
| Kit | Capacity | XMP rating | Timings | Voltage | Rank | Part number |
|---|---|---|---|---|---|---|
| JUHOR | 2×48G | DDR5-5600 | CL46-45-45-90 | 1.25 V | 2R | JHE5600U4648JG |
| GLOWY | 2×16G | DDR5-6400 | CL32-38-38-90 | 1.35 V | 1R | VGM5UH64C32AG-DTACW |
Bring-up and recovery
Earlier attempts starting with the 48G pair or all four DIMMs did not reach BIOS. Working order:
- Install only the 2×16G in
ChannelA-DIMM1/ChannelB-DIMM1. - Enter BIOS and disable XMP.
- Power off and add the 2×48G in DIMM0.
- Allow 1 to 3 minutes for retraining, possibly with several reboots.
- Apply the current settings above.
If failed training prevents BIOS entry, repeat this order; clear CMOS first if necessary. Failed training can silently restore defaults; re-check settings in BIOS afterwards.
Test results
CPU VDD2 entries below are BIOS settings: Auto read 1.104 V in the earlier DRAM tests; the 1.17 V setting reads 1.168 V. These BIOS readings are not measurements during the OS tests.
| CPU VDD2 | DRAM VDD | DRAM VDDQ | Result | Highest sampled DIMM temperature |
|---|---|---|---|---|
| Auto | 1.10 V | 1.10 V | Immediate freezes during memory tests, even 4G. | Not recorded |
| Auto | 1.25 V | 1.25 V | 8G / 32G / 100G short tests passed; llama.cpp load froze. | Not recorded |
| Auto | 1.28 V | 1.28 V | 100G short test passed; daily use froze on 2026-10-08. | Not recorded |
| Auto | 1.282 V | 1.282 V | Display corruption in BIOS. | Not recorded |
| Auto | 1.29 / 1.30 / 1.32 V | 1.29 / 1.30 / 1.32 V | Each setting failed training. | Not recorded |
| 1.13 V | 1.28 V | 1.28 V | BIOS normal; no long test. | Not recorded |
| 1.15 V | 1.28 V | 1.28 V | 100G, 15 minutes: PASS. | 45.5°C* |
| 1.15 V | 1.28 V | 1.28 V | Long test froze; last saved duration 21 min 17 s. | 56.5°C |
| 1.17 V | 1.28 V | 1.28 V | 100G, 6 hours: PASS, 0 errors or hardware incidents. | 56.8°C |
| 1.17 V | 1.28 V | 1.28 V | About 56 hours across three boots ending cleanly; next boot froze during LLM serving (2026-10-11). | 47.2°C in the last available monitoring sample |
| 1.20 V | 1.28 V | 1.28 V | Earlier attempt: BIOS display corruption and freeze within 10 to 20 s. | Not recorded |
| 1.20 V | 1.28 V | 1.28 V | 100G test froze with screen corruption; last saved duration 7 min 23 s (2026-10-11). | 55.25°C |
| 1.18 V | 1.28 V | 1.28 V | 100G test froze with screen corruption; last saved duration 14 min 36 s (2026-10-11). | 59.5°C |
| 1.28 V | 1.28 V | 1.28 V | Reached the desktop, then froze; journal spans 16:30:16 to 16:31:20 (64 s). No recorded pressure test. | Not recorded |
| 1.30 V | 1.28 V | 1.28 V | Set in BIOS only; rolled back without booting or testing. | Not tested |
| 1.17 V | 1.28 V | 1.28 V | 100G, 15 minutes: PASS, 0 errors or hardware incidents (2026-10-11 17:29–17:45). | 59.25°C |
*The 1.15 V short test used sparse temperature samples; its true peak is unknown. The monitored long tests and the 2026-10-11 100G tests sampled about every 5 seconds with a 60°C stop threshold. Saved durations are lower bounds on time before interruption, not exact freeze times.
The passing 1.17 V test ran on 2026-10-09 from 01:29 to 07:30 without swap use. Subsequent daily use included displays on and off with LLM serving. Sleep/wake is untested.
The 1.17 V freeze on 2026-10-11 ended logging at 13:55:46, about 4 h 47 min after boot. Logs stopped during generation without a shutdown sequence or a recorded machine check, BUG or Oops.
BIOS limitations and conclusion
Attempts to apply tRFC 1180 and primary timings 42 / 42 / 42 / 82 reverted automatically after saving, according to the user's BIOS checks. Those relaxed settings never became a tested configuration. The memory frequency control is also locked at 4800 MT/s in the current BIOS setup. The table above retains the last photographed timings; a later readback has not been recorded.
Keep CPU VDD2 at 1.17 V and DRAM VDD/VDDQ at 1.28 V for now. The passing stress test and daily-use record make this the best tested option, but the later freeze means stability remains unresolved.
The user reports a possible ambient temperature rise of about 10°C. Temperature may affect the remaining margin, but neither temperature nor an IMC, DIMM or motherboard fault has been isolated. Manual timing relaxation and frequency reduction are currently unavailable; further tuning is paused. Revisit only if freezes continue or those BIOS controls become usable.