Need help on SO-DIMM RAM

[Carbonx]

I heard that if you have two different size of RAM (for example, 1*8GB in slot 1 & 1*4GB in slot 2) it will act as 2*4GB. If so I want to know that, if I use 4GB as RAMdisk does the rest of the memory act as 2*4GB.

[TempestCatto]

The 8gb and 4gb sticks would give you 12gbs. You will be limited to your slowest stick. So if one does 3200mhz and the other one does 3000mhz, both sticks are limited to 3000mhz. Otherwise, if you need size over speed, it should be fine.

[WoodenMarker]

That's not true. You can use different capacity sticks together for 12gb of total ram. 

You might be misremembering since ram does run at the lower speed of the two sticks when used together.

With RAMDisk, the 4gb assigned will show up as used. The total system memory should still show 12gb. 

Spoiler

 

[Carbonx]

1 hour ago, WoodenMarker said:

That's not true. You can use different capacity sticks together for 12gb of total ram. 

You might be misremembering since ram does run at the lower speed of the two sticks when used together.

With RAMDisk, the 4gb assigned will show up as used. The total system memory should still show 12gb. 

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So does the system use the rest 8GB in 12GB effectively ?

[WoodenMarker]

5 minutes ago, Carbonx said:

So does the system use the rest 8GB in 12GB effectively ?

Yes. If you dedicate 4gb of ram to RAMDisk, 8gb would be left for normal system memory operation. 

[Carbonx]

3 minutes ago, WoodenMarker said:

Yes. If you dedicate 4gb of ram to RAMDisk, 8gb would be left for normal system memory operation. 

How about the performance ? Then why is it suggested to use RAM of same size

[WoodenMarker]

10 minutes ago, Carbonx said:

How about the performance ? Then why is it suggested to use RAM of same size

You'd lose access to dual channel which is substantial and mixing ram isn't guaranteed to work and even less so at their advertised speeds. https://www.gamersnexus.net/guides/1349-ram-how-dual-channel-works-vs-single-channel/Page-3

[Carbonx]

1 hour ago, WoodenMarker said:

You'd lose access to dual channel which is substantial and mixing ram isn't guaranteed to work and even less so at their advertised speeds. https://www.gamersnexus.net/guides/1349-ram-how-dual-channel-works-vs-single-channel/Page-3

What do you mean by mixing RAM

[-rascal-]

36 minutes ago, Carbonx said:

What do you mean by mixing RAM

 

Using a 4GB stick with a different 8GB stick...instead of two matching 4GB sticks, or two matching 8GB sticks.

 

If you use a 4GB stick that is rated for 2400 MHz speed, and 14-14-14-30 timings.

You pair it with a 8GB stick that that is rated for 3000 MHz speed, and 16-16-16-30 timings.

You will need to run all 12GB at the slowest settings of the two.

So... 12GB at 2400 MHz speed, running the slower 16-16-16-30 timings.

[Carbonx]

8 hours ago, -rascal- said:

 

Using a 4GB stick with a different 8GB stick...instead of two matching 4GB sticks, or two matching 8GB sticks.

 

If you use a 4GB stick that is rated for 2400 MHz speed, and 14-14-14-30 timings.

You pair it with a 8GB stick that that is rated for 3000 MHz speed, and 16-16-16-30 timings.

You will need to run all 12GB at the slowest settings of the two.

So... 12GB at 2400 MHz speed, running the slower 16-16-16-30 timings.

Sorry for not mentioning. The two RAM have same speed (ie DDR3L 1600MHz in my case).Only size is different.

[-rascal-]

2 hours ago, Carbonx said:

Sorry for not mentioning. The two RAM have same speed (ie DDR3L 1600MHz in my case).Only size is different.

You should be able to run them at the same speed, timings, and voltage then.

You'll have 12GB of RAM in total.