Mixing memory speeds

[corrado33]

I always wondered about this. What is the issue with mixing memory speeds? Say I have 4 slots on an old motherboard. Two have PC2-5300 and two have PC2-6400 (667 and 800). Is there an issue running like this? Does the faster ram get clocked down to the speed of the slower ram? What would happen if I put one of each stick in each channel. (Channel 1, 1 stick of 667 and one stick of 800, same for channel 2). Basically what would happen if someone stuck identical sticks beside each other instead of using the same colored ram slot? 

 

Also, since I'm here. Which slots should be used first if you only have 2 sticks and 4 slots on the board? Obviously you skip a slot but should the stick or RAM closest to the CPU be in the very closest slot, or the 2nd closest slot? (And subsequently the 2nd stick of ram would either be in the 3rd or 4th slot, respectively.) 

[Oswin]

the faster ram would be clocked down, i dont advice on mixing ram with different clock speeds 

[LukaH]

it clocks down or if you set it to the faster ram it would clock up but you would probably fail to boot because you are essentially overclocking the slower stick. mixing ram is usually a no-no because different timings/settings on the individual sticks of ram would cause blue screens. i do remember that when i was upgrading older systems (not sure if it was ddr1 or ddr2) with different ram sticks it had a little more wiggle room than newer systems. If you have the ram laying around i'd try it and do some testing might be a fun project for a rainy afternoon

 

consult your motherboard manual it usually has directions if you have 1 stick, 2, 3,.... i can tell you that asus boards usually populate ram slots like so (this was on 3 asus boards for amd):

1 stick:  Slot A2 (second from the cpu)

2 sticks: Slot A2 and B2 (second and forth from cpu) 

3 sticks: A2, B2, A1

4 sticks: all the slots duh

[corrado33]

11 minutes ago, LukaH said:

it clocks down or if you set it to the faster ram it would clock up but you would probably fail to boot because you are essentially overclocking the slower stick. mixing ram is usually a no-no because different timings/settings on the individual sticks of ram would cause blue screens. i do remember that when i was upgrading older systems (not sure if it was ddr1 or ddr2) with different ram sticks it had a little more wiggle room than newer systems. If you have the ram laying around i'd try it and do some testing might be a fun project for a rainy afternoon

 

consult your motherboard manual it usually has directions if you have 1 stick, 2, 3,.... i can tell you that asus boards usually populate ram slots like so (this was on 3 asus boards for amd):

1 stick:  Slot A2 (second from the cpu)

2 sticks: Slot A2 and B2 (second and forth from cpu) 

3 sticks: A2, B2, A1

4 sticks: all the slots duh

Interesting. I had originally asked this question because I thought I had mixed ram in an older computer, but looking at the ram now one is marked DDR2 800 and the other is marked DDR2 PC2-6400. Aka the same thing. However, AIDA 64 tells me that the timings are only slightly different. One set (2 sticks) is 5-5-5-14 at 400 MHz and the other is 5-5-5-15 at 400 MHz. However, I THINK my bios allows me to set timings individually for each channel, so I man be able to slow the quicker one down so that the timing's match. I'm not sure about that though.

 

In the end, I'm going to stick identical 2 GB 1066 sticks in each slot for a total of 8 GB, but those sticks are...expensive right now. 

[LukaH]

47 minutes ago, corrado33 said:

Interesting. I had originally asked this question because I thought I had mixed ram in an older computer, but looking at the ram now one is marked DDR2 800 and the other is marked DDR2 PC2-6400. Aka the same thing. However, AIDA 64 tells me that the timings are only slightly different. One set (2 sticks) is 5-5-5-14 at 400 MHz and the other is 5-5-5-15 at 400 MHz. However, I THINK my bios allows me to set timings individually for each channel, so I man be able to slow the quicker one down so that the timing's match. I'm not sure about that though.

 

In the end, I'm going to stick identical 2 GB 1066 sticks in each slot for a total of 8 GB, but those sticks are...expensive right now. 

if you are still on ddr 2 have you considered maybe buying a whole kit (4 sticks) of ram used you might get them cheaper rather than buying new. ram usually doesnt fail and i think most manufacturers put a lifetime warranty on ram.

[corrado33]

1 minute ago, LukaH said:

if you are still on ddr 2 have you considered maybe buying a whole kit (4 sticks) of ram used you might get them cheaper rather than buying new. ram usually doesnt fail and i think most manufacturers put a lifetime warranty on ram.

Interesting, I'll look into that! Thanks. It seems, however, that DDR2 is old enough to command a "premium" now-a-day.  I mean, larger amounts of DDR3 and 4 are much, much cheaper. 

[Sintezza]

Basicly it will allways clock down to the speeds of the lowest ram module and work fine.

However, some motherboards can be very picky and not even boot atall with diffrent ram modules.

So it can be a hit or a miss.

[LukaH]

10 minutes ago, corrado33 said:

Interesting, I'll look into that! Thanks. It seems, however, that DDR2 is old enough to command a "premium" now-a-day.  I mean, larger amounts of DDR3 and 4 are much, much cheaper. 

i know i was searching for some specific ddr3 ram sticks (yes they were a really old model) to add to my existing ram found some at such a price that it was cheaper  to buy a whole new kit (4x4gb corsair ram).

[corrado33]

3 minutes ago, LukaH said:

i know i was searching for some specific ddr3 ram sticks (yes they were a really old model) to add to my existing ram found some at such a price that it was cheaper  to buy a whole new kit (4x4gb corsair ram).

Interesting.

 

Actually I have another question now. Do brands matter if all of the timings match? Or even "types" of ram from the same brand. If they all have the same speed and timings does it matter?

[LukaH]

2 hours ago, corrado33 said:

Interesting.

 

Actually I have another question now. Do brands matter if all of the timings match? Or even "types" of ram from the same brand. If they all have the same speed and timings does it matter?

yes and no. yes if the rams sticks will not play well together, no if you match the timings and have no problems

 

i mean the speed they run at stock is the speed they were tested and approved to run at, anything outside of that range would be considered "unstable". or you can just let the motherboard do it for you and hope for the best. it sets timings that are "most of the time" guaranteed to work