Laptop memory confusion!

Hello,
I am rather confused about my laptop memory. Micron rates it up to DDR3 1600, and the BIOS registers it as DDR3 1333. HP and Intel rate my computer and processor respectively at a paltry DDR3 800 maximum memory speed. SiSandra and PC Wizard both claim that the memory is running at 800mhz, but isn't that DDR3 speed? To further complicate things, PC Wizard shows decreased cpu clock speeds and multiplier while also displaying a higher fsb speed and total bus speed.

What the heck is going on? Can anyone explain this for me; I'm not especially well-versed in how memory works. Screen snips are here for you to look (ignore the highlighting in the one picture that has it).

 

Depends on what CPU and/or chipset you have.

 

No need to be confused! We're here to help. What's happening is that Intel and AMD chipsets, as you might have realized, only support certain memory modules when it comes to their interface specification (DDR, DDR2, DDR3) and their theoretical bandwidth speed (in MHz).

In this case, your computer (CPU) recognizes that you have DDR3 1600MHz memory installed, but the BIOS (chipset) sees it as DDR3 1333MHz. This is due to the fact that the chipset your laptop's motherboard is running can only recognize memory with a maximum speed of 1333MHz. Therefore, the chipset will (safely) downclock your DDR3 1600MHz memory to 1333MHz in order for it to be compatible for use.

 

Try those pictures again. Also naming conventions for RAM are a little off. One man's 800 is another man's 1600 based on what they decide to be the frequency, though this may or may not be the case for you. So you know you have DDR3 1600 in there. It is unlikely that your laptop accepts up the DDR3 1600, so it is likely to just run at DDR3 1333. Those pictures and maybe some more info about your system might help clear things up.

 

Thank you so much for the replies.
It is an HP Tm2-1100 with an i5-430UM, and the intel website says it can only support memory speeds up to DDR3 800 which I thought means 400mhz. SiSandra reports 667mhz for the memory module specs and 800mhz for the running speed. However, the timings in those pictures I listed are not the PC3 12800 timings associated with these memory modules.

There is also the anomaly of the bus speed being actually faster than the CPU speed in the PC Wizard report. Is it possible that this particular chipset and CPU clock the bus speed to accommodate maximum memory speed so that more memory bandwidth is available to the processor as turbo-boost ramps up the CPU frequency? I've never heard of that happening before, but I'm fairly new to all of these concepts behind front side bus speed, CPU frequency, and memory speed.

 

Well, part of the problem is that you don't have any pictures up, so we're just going from what you've told us so far. 800 MHz running speed would seem to fit, as that seems to be the limit of the i5-430UM low voltage CPU. 667 MHz for the memory module specs would fit for DDR3-1333 memory (667 Mhz being the I/O bus clock at that point), and it would just be running slower than the maximum possible (1333). Timings usually adjust to the actual running speed, so since the RAM is running at speeds less than PC3 12800, the timing will also adjust down to match (probably to the 5-5-5 or 6-6-6 of PC3-6400, which is what DDR3-800 should be running at).

 

Oh, my bad! Ok, I'll try them again. I didn't realize that that's what Trottel meant by "try those pictures again." I'm an idiot lol. Here they are.

 

Here is another picture and the datasheet for my memory modules.

 

Those pictures show:
- You have DDR3- 1600 RAM installed (DDR3-SDRAM: PC3-12800 ( 800Mhz))
- Your system is running that RAM at DDR3- 1333 speeds (DDR3-SDRAM PC3-10700 @ 667Mhz)

The way to pick apart the naming convention:
DDR3-1600 SDRAM: PC3-12800 800Mhz

Tells you what kind of memory it is:
- DDR3 = Double Data Rate 3.
- SDRAM = Synchronous Dynamic Random Access Memory

Tells you speeds and transfer rates:
- 800Mhz = The I/O bus clock speed (in Mhz)
- 1600 = Data rate (in millions of transfers per second). Also called internal clock cycle. DDR memory transfers at both the rising edge and falling edge of the I/O bus clock, so its internal clock cycle is 2x the I/O bus clock speed.
PC3-12800 = Module name. 12800 refers to the peak transfer rate (in MB/s)

DDR3 performs 8 data transfers per internal clock cycle (data rate).
1600 (data rate) * 8 (# of data transfers) = 12800 (peak transfer rate).

In short, everything is fine in Spiritus-World.

 

That's odd how the RAM is listed as PC3-12800 in one place, and PC3-10700 right below it. From looking at the model number, it appears that both of your RAM sticks appear to actually be 1333 MT/s sticks, and not 1600, so PC3-10700 should be correct. Not sure why it states PC3-12800 in that case. And as is sort of shown in your last picture, 6-6-6-15 timings would seem to be just right for 400 MHz (right between the 381 MHz 5-5-5-14 and the 457 MHz 6-6-6-16), which would mean an effective speed of 800 MT/s. You might want to consider trying the program CPU-Z to get this sort of information; its one that most of us tend to be a little more familiar with.

Edit - Kent1146 posted while I was gathering information. I think I disagree with him in detail, but not in the final analysis; that is, everything is fine.

 

Yeah, that is weird about the model number.

You do indeed own PC3-10700 DDR3-1333 RAM.

 

Actually, I own PC3-12800 DDR3-1600 RAM; the datasheet I posted says so, and it is directly off of the Micron website.

PC Wizard is made by the same people that make CPU-Z; when I looked at CPU-Z just now, though, it showed my memory as operating at 399.1mhz, so DDR3-800 it is, according to CPU-Z.

I wish I could increase my front side bus to squeeze more than half of my RAM's potential out of it.

 

Actually, the datasheet says that according to your part number (G4D1) it's a DDR3-1333 (top of page 2). That's assuming they kept the same conventions, since the rest of your part number doesn't quite match up.

 

Ah, yes. You are right; sorry. I'm still very new to all of this, but that's why I come to forums to ask people who know more than I do
Thank you so much, guys.