Plug-in a DDR2 800MHz to a slot that can handle up to 667MHz only

Question

I have an old computer that has an ASUS P5S-MX SE motherboard, and only have a 1GB RAM. So I planned to upgrade the RAM and buy a 2GB RAM. Only DDR2 can be installed in the motherboard. So I looked up on the internet and found a second hand 2GB RAM DDR2.

My only mistake is that I didn't considered before buying was the MHz, and found out that the DDR2 I bought was 800MHz. Knowing that my motherboard can only handle up to 667MHz only.

Question 1:

Is it still gonna work with my motherboard? I'm now planning to remove the 1GB RAM and replace it with my newly bought DDR2 2GB 800MHz.

Question 2:

If it is, are there any disadvantages or cons?

Question 3:

If it is, is it okay to have them both installed in my motherboard? One 1GB DDR2 667MHz and one 2GB DDR2 800MHz? Are there any disadvantages if they are both installed in my motherboard?

Question 4:

If having a 2GB DDR2 800MHz and a 1GB DDR2 667MHz is not compatible. Can I have two 2GB DDR2 800MHz installed, in slots that can only handle up to 667MHz only, in my motherboard? Will it not affect other circuits or power?

Solution

The DDR2 RAM can be run at lower frequency without any issue. The motherboard will run the RAM at 667MHz instead of 800MHz and everything will be fine. The disadvantage is that you lose a bit of performance from the lower frequency.

Comments

[Logan Wayne]

Thanks! So will it still be okay if I just put it on the motherboard with my other/older 1gb RAM 667mHz? Or just replace it? Because they are not compatible with each other?

[Mokubai]

Technically he won't loose system performance as it would never have run that fast to begin with. The only real loss would be money if the 800MHz stick costs more then the 667. @LoganWayne most memory sticks will be able to work with slower sticks and should work at the frequency of the slowest module. Some times they don't, but more often than not you should be able to use new memory with old.

[Logan Wayne]

Thanks, @Mokubai! Okay, I'm set. The disadvantage is the cost of those RAM. So it is okay to just replace the old one (667MHz) with the new one (800MHz). Can I ask again? So I replaced the old one with 2GB DDR2 800MHz, can I install it with the same RAM? Two 2GB DDR2 800MHz in those two slots (667MHz)? It won't affect other circuits or power?

[ilkhd]

No, you'll be fine.

[Logan Wayne]

@ilkhd - what's your proof or reasoning? :D Okay. I'll try to find another 2GB DDR2 800MHz. Thanks, guys!

[ilkhd]

Power consumption of devices with higher frequency rating usually same or lower (when used at lower freq) than of lower rated devices.

[Logan Wayne]

Hi guys! I installed the RAM. When I view my Computer details. It says that 2.00 GB RAM (1.87 GB usable). Why only 1.87GB? Is it because of the MHz?

[magicandre1981]

look in msconfig if you limited the RAM usage to 2GB (Perf myth). With perf loose I mean that you waste some performance by running a memory at 667MHz while it can run at 800Mhz.

[Logan Wayne]

@magicandre1981 - Okay. I'll check the max mem in my msconfig later when I get home (like after 9 hours). And that is what I thought also last night, maybe because of the MHz, the RAM lose a bit of performance. So If I buy the same brand and model of that RAM, I'll just get a total of 3.74 usable memory? Thanks!