Crashing seems to be bad RAM timing?

[john.r.moser]

I'm using an ASUS TUF Gaming B450-pro with G.Skill DDR4-3200MHz.

According to G.Skill, this RAM runs at 3200MHz, 16-18-18-18-38 timing. Without XMP enabled, it runs at 2133MHz, 15-15-15-15-36 timing.

My motherboard auto-detects this without XMP as 2133MHz, 11-11-11-11-27 timing.

In case you don't understand what all that means: certain operations inside the RAM are electrically too slow to keep up with the timing, so there's a delay where the CPU waits when switching rows or column addresses so all the electrical signals can make it where they're going; the RAM operates in burst mode, so after you say "go to address X and get me 20MiB of data" (e.g. DMA copy a contiguous block to video card), it dumps 20MiB of data from the bus at two words (in this case, 64-bit wide words, so 128 bits of data) per clock cycle, instead of waiting 16 clocks or 38 clocks or whatnot.

Hilarity ensues.

Propagation delay is affected by temperature, so if you put more load on the RAM, things break.

Let's see if this remains stable now.

[Coops]

If you didn't mess with the voltage or the timings in the BIOS, then the board should use a stable configuration. Have you run Memtest+ or Prime95 ?

[john.r.moser]

Originally posted by Coops:

If you didn't mess with the voltage or the timings in the BIOS, then the board should use a stable configuration. Have you run Memtest+ or Prime95 ?

I didn't mess with it in the BIOS; it was set to auto. According to the manufacturer, this model of RAM should be 15-15-15-15-36, except in XMP mode where it should be 16-18-18-18-38. Currently, the BIOS lists the parameters it thinks I should use as 11-11-11-11-27, with the box next to those parameters having my custom settings of 15-15-15-15-36. The BIOS should be getting these figures through JEDEC, so either the BIOS has bad code or the RAM is exposing incorrect timings via JEDEC. The timings it selects in XMP mode, by contrast, match the 16-18-18-18-38 figures as per the manufacturer.

There comes a point when the signal can't physically make it down the wire that fast; the default settings blow way past that point.

[Coops]

11-11-11-11 seems really aggressive. I would try the 15's or bump the voltage.
testing with Memtest86 should let you know if you have bad memory or bad settings.

[Tarzan]

Have you tried a bios update?