XPS 8940, RAM upgrade issue with Crucial Ballistix RAM

@thalaivar Usually Crucial memory is pretty reliable, I am not sure why it did not work, but it is possible it is your memory configuration. Did you leave the original 8GB in the PC? What was your original 8GB configuration, 2 x 4GB or 1 x 8GB?. Did you install the Crucial memory in slots with matching colored securing clips?

See the last entry in this post, it is a list of memory that seems to work.

The PC came with a single stick Hynix 8GB DDR4-3200 RAM.  I removed that from Dimm 1 slot and put in the Crucial Ballistix RAM in Dimm Slots 1 and 2 (the ones with the white locking clips; the other two have black locking clips).  When this didn't work (2 amber / 4 white flashes), I removed one stick (from Slot 2) and tried with the new RAM only in Slot 1.  That didn't work either.  I then swapped the other stick in Slot 1 and that didn't help either.  Same pattern with the flashes (2 amber / 4 white).

I then removed the Crucial RAM and put back the Hynix RAM and it boots and works without any issues (It did come up to POST screen about memory error that happened).

Looking forward to what you find out. I want to go from 16 to 32 at some point and your solution will help us all. 

Good Luck.

Scott

@thalaivar  - Did you try clearing BIOS with the 2 new modules installed?

@thalaivar It appears that the memory that Dell uses in the XPS 8940 is 1.2v and the Crucial memory you have is 1.35v. I don't know if this is the problem but this FAQ only lists 1.2v memory for the XPS 8940. In addition, the post I reference before that lists a Crucial 2 x 8GB kit that works is also 1.2v.

I initiated a chat with Crucial tech support and they were pretty helpful in diagnosing the issue.  It looks like one of the 2 sticks is bad and when I was switching the RAM sticks in Dimm 1, I had to also hold down the power button for about 5 to 10 seconds (with the AC cord unplugged) to reset any residue power in the circuit (not very technical - but that's what it sounded like the agent wanted me to do).

But since it was a kit (8GB x 2) that I bought from Newegg, I have to return both and get the kit replaced.  Waiting for UPS to pick up the package back to Newegg and have to wait for a new kit to arrive.

Bottom line, it looks like the 1.35v RAM will work in the Dell XPS 8940 - it just appears to be a bad module.  I did not have to do anything in Bios as per the tech support person - just had to do that power cycle thing each time I tried with a different RAM combination. (2 sticks in slot 1 and 2; Stick A in Slot 1; Stick B in Slot 1; Original Hynix RAM in Slot 1).

@thalaivar  - Glad you got it sorted. Surprising it was a bum module, especially since it's Ballistic.

Though I'm not sure Ballistic is worth the extra cost and hype...

@thalaivar I am curious what happens if you put in the working Crucial module paired with the Hynix module.

@thalaivar The Hynix memory that came with your XPS 8940 is 3200 MHz; it is stated so in the Setup and Specifications. The speed you saw, 1600 MHz, is the DRAM frequency the memory is clocked at but this is Double Data Rate (DDR) memory so the memory speed is 3200 MHz but Dell limits it to 2933 MHz for an i7/i9 CPU or 2666 MHz for an i3/i5 CPU. 

The reason I asked about trying the Crucial and Hynix memory was that I was going to suggest you match Hynix memory with a single Crucial 8GB memory module and save yourself some money. It was also the reason I asked you earlier about your 8GB configuration, whether it was 1 x 8GB or 2 x 4GB.

@Vic384 - Ha!  I was curious too and so I tried it with the Crucial in Slot 1 and the Hynix in Slot 2.  It does work and Windows 10 shows 16GB in the installed RAM.  Although I would think it would work in the lower MHz (probably the 1600Mhz that the Hynix is rated at)  and at the highest latency (19 which is the Hynix).  I wish I had taken screenshots of the memories installed in CPU-Z before I packed and returned the Crucial.  Oh well.

@Vic384 - ah, gotcha!  I guess it is a little late for that since I had spent about $72 for the Crucial Ballistix 16gb kit and Newegg has about $22 in restocking and shipping (back to them) fees.  I really hope that the replacement kit works (both modules) and I can possibly eBay the 8GB Hynix memory for $20 or so.

@thalaivar Dell sells the Hynix equivalent 8GB memory module for $84.60 probably close to what you paid for your 16GB.

@Vic384 - oh wow!  That seems extremely pricey from Dell!  It is like the printers and cartridges game.  Extremely cheap printers and pricey cartridges and other components.