Question DDR3 problem with CL9 vs CL11

[Gswiss]

I'm using a Toshiba Satellite Pro C70 notebook with a single Samsung DDR3-1600 CL11 (4 MB - 64 bits). When I install a 4MB Corsair Vengeance DDR3-1600 CL9 in the empty slot for a total of 8MB, the notebook won't start at all.

I tried other combinations to no avail: 2 Corsairs followed by a single Corsair all by itself replacing the Samsung. The notebook will only light up with the single Samsung.

I'm surprised the latency has that effect. Would you have an explanation?

 

[VirtualLarry]

what's the voltage rating on the RAM sticks? That might be the real issue here.

 

[Gswiss]

what's the voltage rating on the RAM sticks? That might be the real issue here.

Thank you, you probably hit it right on the nail. It was difficult to identify the installed memory stick's voltage. Neither Aida nor cpu-z provided the information. Speccy did. The installed stick uses 1.35V while the Corsairs I bought run at 1.5V like most sticks (Samsung sticks appear to be available at 1.35V and 1.5V).

When I purchased the sticks, the seller was young. He didn't bother enquiring about the voltage. The bottom line is: always deal with a medium-aged or old guy.

 

[VirtualLarry]

The bottom line is: always deal with a medium-aged or old guy.

In the 90s PC era, generally the sage advice, was to ask for "the guy in the back" of the PC store, wearing the long hair and the Grateful Dead t-shirt. Or go by beard length. The longer the beard, the more "guru" the guy was. OK, ok, I know, pretty superficial. But generally you're right, the older guys in the biz know more than the pimply-faced younger geeks generally staffing the customer-facing roles. Well, back in the day when we had person-to-person PC shops. Now it's nearly all internet mail-order, and you're trying to figure out parts compatibility, from the myriad internet reviews for the part, all while ingesting a large grain of salt.

 

[VirtualLarry]

To further clarify, nearly all DDR3 SO-DIMM using laptops these days, use "DDR3L", the "L" suffix standing for "Low-Voltage". Generally, "Standard Voltage" DDR3 SO-DIMMs were 1.5V, and DDR3L SO-DIMMs were 1.35V, although there were a few that were 1.25V as well.

So, to narrow your search, get some DDR3L-1600 SO-DIMMs, with CAS11. That should work. CAS9 may work, but it's not guaranteed, depending on OEM laptop BIOS programming.

Edit: You can always use the Crucial Memory Scanner ( www.crucial.com ), which will scan your laptop (or desktop), and recommend memory that should be guaranteed to work. You might pay a little more, but their prices are generally competitive with the market.

 

[DrMrLordX]

I'm surprised the latency has that effect. Would you have an explanation?

The real question is: what timings is the system trying to give the new and old SODIMMs? If you have mismatched DIMMs programmed for different default settings, on a desktop system, usually you have to lower the speed/timings of the faster DIMM to match the slower DIMM. The system may not do that automatically and try to use the speed/timings of the faster SODIMM on your laptop, which will lead to a failure to POST if the memory can't even train correctly.

 

[Gswiss]

Many thanks to both of you for your observations.

I try to avoid purchases through the Web in order to encourage shops like the one where I bought the Corsair sticks. You always pick up useful info when you chat with the geeks, even if you pay a bit more. In this particular case, it was the first time in years I came across a techie in that shop who lacked the know-how (asking whether I was using 1.35 or 1.5V memory sticks on that notebook).