X58A-UD3R amber CPU-volt LED for DDR3-1600

[Gary123]

I've changed the BIOS settings to run my DDR3-1600 RAM at 1600 (previously at 1066 by default). Settings are 12x(1600) 8-8-8-24/88 1.64v.

Everything's running great, and as expected the green DDR-voltage LED is illuminated. In addition, the green and amber CPU-voltage LEDs are lit. (There's no CPU OCing, only the memory tweaks just listed.) I assume the CPU-voltage lights are because the memory controller is in the i7-950 processor, so it's affected by the DRAM voltage. But is it normal to have an amber light for CPU voltage, not just a green light? (Core temps are fine and no other LEDs are lit.)

GA-X58A-UD3Rr2(FB)  i7-950  OCZ3G1600LV6GK(6GB)  AntecEarthWatts650W  CoolerMasterHyper212+

[Dark Mantis]

The first thing I would say is that it is not something to worry about. I am suprised that your OCZ memory is happy at 1.64v as usually OCZ is a bit of a power hogger. My Corsair 1600 Dominators actually need at more than that  to run using their XMP settings. On my board the green lights are on as expected but there is no other amber for the CPU. I can only assume that it is a borderline setting and yours just sets it off.

[Lsdmeasap]

The Amber CPU LED is likely high QPI/Vtt

Check with easytune in the Tuner tab, advanced, voltage I - and see what Target QPI/Vtt is on the right side.

[Gary123]

The Amber CPU LED is likely high QPI/Vtt

Check with easytune in the Tuner tab, advanced, voltage I - and see what Target QPI/Vtt is on the right side.

You're right. I didn't change the QPI/Vtt setting in the BIOS (it's still set to Auto, with a normal value of 1.175v), but EasyTune shows a target of 1.435v.

I don't know how or why that target got set, or whether it's harmful, or whether I should manually set it lower in the BIOS. Any advice is appreciated.

[Gary123]

I noticed in Table 2-6 on p. 22 of Intel's i7-900 Series spec that 1.35v is listed as absolute maximum for Vtta and Vttd ("Excessive overshoot or undershoot on any signal will likely result in permanent damage to the processor"). So I set Vtt to 1.335v in the BIOS. Now the amber CPU-voltage light is off (only the green LED is still lit), and the PC seems to be running fine (though I haven't re-run memtest yet). I hope a couple of days with Vtt at 1.435v hasn't caused any latent damage.