How to match RAM?

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sally_91

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Dec 22, 2012
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I took the RAM out of my computer and took a picture of the info stuck to the sides. This is what it says on 1 stick:


CORSAIR - VENGEANCE LP
CML16GX3M4A1866C9
16GB(4X4GB)
320142 / 320143(2nd stick)
125001434
1866 MHz
9- 10 - 9 - 27
1.50V
ver8.16

I know it's not guaranteed to work 100% if add to my current RAM setup right now, but I'm gonna take the chance and try it anyway.

I just need to know which of these details have to be the same in the RAM that I need to buy.

Also, does it matter if it's an odd number of RAM total? Like using the original RAM set with a different sized RAM set. (dumb question)
I found some Corsair Vengeance LP sticks with the same frequency and timings.
But I also found Corsair Vengeance sticks just like that one, for much cheaper but weren't Low Profile. If the only difference was the form factor, does it matter?



I bought my computer from CyberPowerPC and for some reason they gave me 2 4GB sticks that belonged to a 16GB set. I only have 8GB of RAM.
They also used RAM that isn't explicitly supported by my motherboard.
It says on the Gigabyte website that it has support for DDR3 2200(OC)/1600/1333/1066 MHz memory modules.
The one they gave me is 1866 MHz.

 
In general, u want to have all sticks to have the same speed, latency, voltage, and DDR3 of course.
If u mix sticks with different speed, then they will just down clock to the lowest among them.
You dont need to care about low profile or not, unless u have a fancy air cooler with poor ram height compatibility
 


You didn't mention the timing. Does it not have to match?
Unless timing is latency (I'm pretty new to all this)
 
real quick, i'm looking at 2 ebay listings.

-One is for an 8GB RAM module that belonged to an 8X8GB (64GB) set
-Another is for a 2X8GB RAM (16GB)

Can I mix either with my current RAM setup:
2 4GB RAM modules that belonged to a 16GB set

My motherboard has 4 slots and is dual channel

I remember hearing that if you have 4 slots, then you should either use 2 at a time or 4 at a time, but not 1 or 3 at a time?
 
Sorry for late reply, but latency is just one of the parameters of ram timings (tCL, tRCD, tRP, and tRAS)
Well I guess u can find related post here, or google them if u really wish to dig further :)
It is ok to use 3 sticks, one pair of them will be running in dual channel, and the leftover stick in single channel.
3 sticks or 4 sticks, the difference is really not significant
 
Okay great! I ordered a set of 2X8GB(16GB) sticks on eBay that came in the mail yesterday.
They have the same specs as my current RAM except that they're not low profile.

According to item 7 in this Tom's Hardware article, I can mix varying RAM sizes by virtue of Flex Mode.

I just need some help on which configuration to set up my RAM by and also if there are any precautions I should follow before/after doing so.

This is my collective RAM:

CORSAIR - VENGEANCE LP
4GB
CORSAIR - VENGEANCE LP
4GB
CORSAIR - VENGEANCE
8GB
CORSAIR - VENGEANCE
8GB

This is a page out of my motherboard's manual on installing the memory:
Screenshot_2017_12_1_mb_manual_ga_b75m_d3h_e_pdf.png


I don't know if it should go 8-4-8-4(from left to right) like the example in the Tom's Hardware article or some other way. If someone could help me out on how to get it going I would really appreciate it.
 
I added the 2X8GB of RAM and the computer would start but not boot. Am I doing something wrong?

I went into the BIOS and loaded the optimized defaults. That changed AHCI to IDE so Windows wouldn't start. So I loaded the optimized defaults again except with one change; change IDE back to AHCI. That let PC go into Windows.

I have 2 white RAM slots and 2 blue RAM slots on my motherboard. I tried taking out the old set and putting in the RAM that I just bought. The PC still wouldn't start. I tried just 1 stick. Same result. I tried using the 2 white slots. Nothing. The 2 blue slots. Nothing.

I tried one of my original sticks and combined it with one of the "new" sticks. Nothing. My old set works on all 4 of the RAM slots.
So I'm not sure what to do. Did I buy RAM that is defective?
 


The motherboard is a Gigabyte B75M-D3H - LGA 1155
The CPU is an Intel i5 3570

The "Ver" number on the Corsair 8GB memory module is 8.22
 
Thanks for the extra details!

The 8 GB Corsair modules should be compatible with the computer.

With the computer powered off AND with the PSU switched off, wait a minute or so. Then install ONLY the two 8 GB modules either in the black slots, or in the blue slots, then clear CMOS.

Switch PSU back on and restart computer.
 


I was able to get the new sticks working!
First I tried each stick separately on the 1st slot. They both worked by themselves. Then I tried both at the same time. The computer wouldn't start but I found out it was just a re-seating issue. I heard the corresponding slot click but I guess it wasn't in all the way.

So the 16GB are detected and confirmed working. I tried putting in the two 4GB sticks one by one on the remaining 2 slots but the PC wouldn't boot? The remaining slots are where I had the 4GB sticks in, the past day or so, and they were working fine. They were originally in the other set of slots, and were working in there as well.

Is there a way to get everything working together at the same time?


 
OK. We're making progress.

There is the possible issue of inter-module incompatibility due to variations in module characteristics. This applies mainly when using different modules, but it can also happen when using same (individual) modules.

For best memory performance, the 4 GB modules should be in one color slot, and the 8 GB modules should be installed in the other color slot. So there should be 12 GB per channel, making a total of 24 GB.

Memory arrangement could be 4 GB, 8 GB, and 4 GB, 8 GB. OR, 8 GB, 4 GB, and 8 GB, 4 GB.

No guarantee of success, but to get all the modules working together, increase the DRAM Voltage in BIOS by 0.05 V. Note that it is not recommended to exceed 1.65 V.
 
Thanks for helping me out.

The DRAM Voltage was originally at 1.50
I increased it to 1.55 but it changed it to 1.56
I turned off the computer, waited a minute, then put in one of the 4GB modules in one of the other colored slots.

It wouldn't boot.
I increased the DRAM Voltage to 1.60
Same result

Should I try 1.65 V?
 
Yes, you can go up to 1.65 V safely. Although the DRAM Voltage can actually go higher than 1.65 V, it is not recommended doing so.

If there are still problems, the memory controller voltage could be increased also. But it is not known if that option is available on your motherboard. If it is available it might be labelled something like VCCSA, or CPU Service Agent Voltage. This voltage could be increased by 0.01 V.
 


The DRAM Voltage seems to only rise by 0.02 from 1.56
So that would include 1.58, 1.60, 1.62, and 1.64 and then 1.66
I didn't want to try 1.66

I read that VCCSA used to be called VTT.
In the Gigabyte BIOS, I saw that there was a "Profile VTT Voltage":

But its parameters are greyed out.
 
Limit DRAM Voltage setting to 1.64 V, for now.

For the i5-3570K third generation CPU, the memory controller voltage control should be labelled as System Agent or VCCSA (or something very similar) as mentioned before, but this may be dependent on the BIOS used for the system.

Profile VTT Voltage is the termination voltage for the memory and is not the memory controller voltage. Actually this voltage should, generally, be within 0.5 V of the DRAM Voltage. So if DRAM Voltage is set at 1.64 V, then the VTT Voltage should be at least 1.14 V (or a bit higher).

Greyed out probably because the memory settings are being run automatically by BIOS. Manual control of memory settings would be required to enable greyed out BIOS memory setting options.
 
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