PC3L will POST, won't boot

Having bought a new laptop I thought I'd be smart, max out its RAM and then "trickle down" the modules I took out of it into my older laptop that I use as a workstation.

Now, my new laptop is an Alienware 15 (2015) and my older laptop is a Dell Studio 1749.

The AW came with 2x4GB modules and I was running 1x4GB and 1x2GB in the studio. No problems.

Replaced the AW's memory and fitted it to the studio. When I try and boot it it POSTs OK, but windows doesn't even flash it's loading screen before rebooting. When I leave the "old" 4GB in there and replace the 2GB with a module from the AW it briefly shows the windows loading screen before bluescreening and restarting.

Clearly the Studio isn't compatible with the AW memory. Slightly surprised that it will clear POST, but I guess POST doesn't actually write data to the memory, just checks it's there.

What I don't understand is why this isn't working. The Studio's memory is PC3 1.35V, whereas the AW's is PC3L. However, my understanding was that the only difference between the two is that PC3 was originally 1.50V, whereas PC3L is 1.35V. As my system can use 1.35V memory, what have I misunderstood/missed?

Hope I haven't fried the PC3L memory.....

 

It's more likely the speed, rather than voltage. I'm using PC3L modules in my PC3 machine, no problems. The thing is to check the max rated speed, both on the modules and your machine. My 8740w can go up to 1333MHz, and I got 1600MHz modules. They can safely downclock to 1333MHz, not so sure about 1866MHz and up modules.

Also the CPU matters as well, if it's i5 I think they can go 1066MHz max, not very sure, since I never looked at i5s, but something you should check as well.

 

Interesting thought. The AW modules are 12800S, whereas the ones in the Studio are just listed as 12800 (the 4GB one certainly is, I'll have to open it up again to check the 2GB one). My understanding is that the "S" means SO-DIMM, so they're actually the same?

You are correct that this i5 is limited to 1066MHz. I too thought they'd happily downclock.

 

phoenixhd, if Alienware modules are high density (less chips), it is the usual incompatibility problem, no way around it other than using low density modules.

 

The Studio 1749 is a 5 year old computer and I doubt if it will run on pure 1.35V RAM (as opposed to the 1.5V/1.35V modules). This review gives me a CPU and thee is no hint of low voltage RAM in the CPU specs.

John