RAM with too good CL for HP BIOS

[Ron5553792]

Known issue but wondering if anyone has updates.

HP BIOS can handle getting a DDR4 RAM stick that is too fast, eg 3200Mhz, on my elitebook 830 g5 or g6 which only supports 2400Mhz. Basically system just downgrades to 2400 (thus not utilising full speed), which is ok. The spec sheet only ever promised 2400Mhz.

However, when CAS latency is too low, eg HyperX Impact 2x16GB 2400mhz has CL14, then the system goes nuts on reboot, ie works ok at first but after next restart stops working. Everyone thinks it's a BIOS issue and I think that is the most likely culprit.

The workarounds are to pair with another sodimm stick with latency of CL15 or higher, or buy another set with CL15 or higher.  Not happy with either option... So:

1) a new bios came out recently in may. Anyone tried it and getting different results, or same problem still? Since the CL14s do work the first time around, I'm convinced there is a BIOS workaround but I don't see it yet... Something that tells the system the memory sticks are new and can operate at CL14 (because it does normally until restarted).

2) HyperX Impact black runs at 2666Mhz CL15, so should work, but wanted to check if anyone else has tried these ones specifically? Alternatively gskill ripjaws have a 2800mhz CL15. These are actually cheaper than the stock 2400/2600 CL17 recommended by the hp manual.

Side note digression: kind of a waste to stick a 2666mhz memory stick on a laptop with max 2400mhz speed, which was the case on my g6.

[Ron5553792]

Just summarising what I have seen from previous threads on the DDR4 RAM upgrades that work and don't:

Works:

Hynix 1x8GB CL17 2666Mhz (stock)

Samsung 1x16GB CL17 2666Mhz (stock)

Crucial 2x16GB CL17 2400Mhz

Crucial Ballistix 2x16GB CL16 2400Mhz

Patriot Viper 2x16GB CL16 2400

(using any of the above on 1 of the 2 slots also works)

(presumably anything with CL>17 is also ok but works less optimal)

(presumably anything with speed >2400Mhz is also ok but gets downgraded to 2400Mhz)

Does not work:

HyperX Impact 2x16GB CL14 2400Mhz

(presumably anything with CL<15 also does not work)

Would be interesting to test and collect data on:

HyperX Impact 2x16GB CL15 2666Mhz (this would prove issue is not HyperX specific)

Any difference in motherboards (e.g. 100 series vs 200 series vs whatever the Omen ones are)

[Ron5553792]

All of the above I tested with an Elitebook 830 G5, and I assumed it would have the same results in my Elitebook 830 G6 but I was mistaken. So far all of the above works with the G6 (including the HyperX Impact 2400 CL14 that crashes on restart with the G5), which has left me puzzled.

Looking closer, the G6 has a different motherboard (200 series Vs 100 series) than the G5, which of course means different BIOS, which you can see in the version numbering.

In summary, pretty much everything works on the G6, and only 2x16GB HyperX Impact 2400 CL14 doesn't work in the G5 (I ended up with 2x16GB 2666 CL15 Vengeance, but all the mixed combos I tried also worked ok). 

[Ron5553792]

Some of the details.

On my 830 G5, the motherboard is 83B3 with BIOS Q78 Ver. 01.11.01. I downloaded the BIOS early Aug 2020. I replicated earlier reports that the HyperX Impact 2400 CL14 (2x16GB)  would work on initial boot but then hang on restart.  It was quite stable while I was using it, which supports earlier theories that it is a BIOS issue, e.g. some kind of bug when timing tables are changed or refreshed, rather than a physical hardware limitation - but I wouldn't take that to the bank. I now have 2x16GB Crucial Vengeance 2666 CL16 on there, with actual CAS = 16 but DRAM frequency under 1200 (ie. throttles to 2400 and does not use the full 2666, as expected). I have also tried a number of different configs, which also worked ok. So it appears only the 2x16GB 2400 CL14's that were the problem. I would be curious if the HyperX Impact 2x16GB 2600 CL15's had the same problem, because that would narrow down the issue to either the HyperX Impact SODIMMs or the CL14 timing.

On my G6, the motherboard is an 854A with BIOS R70 Ver 01.05.03. I downloaded the BIOS in early August 2020. I was unable to replicate any of the problems. I now use those HyperX Impact 2x16GB 2400 CL14's.  Has been working fine, though CPU-Z shows the CAS latency and DRAM frequency to fluctuate much more on the G6 than G5. Specifically, it goes from 1200mhz + 14 clocks to 664mhz + 9 clocks and back. Maybe that means something maybe not. I have not run Memtest on either machine yet. All I can report is that the crash on restart issue is not there.