Memory Speed Mixing... bad!?

[Morazl]

I'm at work and a computer was brought in that had been "fixed" by a fellow employee. He added ram to the board, it has 2 DIMMS and the computer is a Dell Optiplex GX270.

Dell states this model has a Intel 865G chipset and supports DDR 333/400.

I try to turn the computer on and get nothing but and orange LED blinking on the power button, I open the case and examine components, everything looked fine until I saw the RAM..

Stick #1: 512mb DDR333 (some generic brand, a symbol of an M with a circle around it)
Stick #2: 512mb DDR400 (Dell branded, assuming this is the stick he added)

As far as I know, running two different speeds of ram has been a no no. I swapped the two sticks so the DDR400 is in slot 2, and the DDR333 in slot 1. (I read somewhere that it works better that way) and the computer will now boot up, get into windows and the computer completely shuts off after 10-15 minutes.

I'm not really looking for a resolution, I just want to be able to prove my fellow co-worker f'd up and be able to call him out on it while being absolutely sure I'm correct before doing so.

 

[BillLeeLee]

You can mix RAM speeds, but sometimes it does not work as well as you'd like. I have systems that are running DDR400 and DDR466, and back then mixed RAM that was DDR266 with DDR400.
RAM timings and such could also be a problem, if you're putting performance type RAM into an OEM machine like a Dell which requires different voltage settings or such.

But typically, memory are compatible with slower speeds and you should be able to mix them.

And the M with a circle around it is Micron, or the company that pretty much provides all the chips for performance memory and Crucial memory.

 

[Nenu]

If the timings each stick uses cant be matched (ie one requires a timing that the other cant use and autodetect uses the wrong timings) or one stick cant run at the speed/voltage required it will cause an issue.
If you take care that the memory will not conflict with the above, it should work.
Setting the speeds/timings manually can get round many issues where the auto detected speeds/timings are not compatible but this shouldnt have a place in a business PC.

In my earlier years I did a lot of memory upgrades on older systems and now supervise issues on newer systems. There can be some strange problems.
In your case you dont yet know the cause of the problem.
It might be an incompatible memory module, then again, there may be a fault on the motherboard or the new module might have a fault.

Assuming you dont mind keeping this ram...
The speed/timings could be set wrong such that a small adjustment solves the problem.
It may not be possible to set the speed/timings in the CMOS as its a Dell but if possible I would set the memory speed to DDR333 in case they are both trying to run at DDR400 with the new faster stick in place.

If adjusting memory speeds/timings manually solves the problem, a note to that effect (and a phone number to call for support) should be left on the PC in case the CMOS gets reset.
However, in a business environment, I recommend fitting memory that will work with no intervention.

 

[Morazl]

awesome reply, thank you.

I ran memtest 86 for over four hours without any errors or stability issues (after switching the order of the two sticks) if there are any further problems I will be sure to try what you have suggested.

 

[lagos]

awesome reply, thank you.

I ran memtest 86 for over four hours without any errors or stability issues (after switching the order of the two sticks) if there are any further problems I will be sure to try what you have suggested.

after passing the mem tests, load up a stress test like prime95 along with mother board monitor to help test the system even more. for all you know, the problem could be related to a poorly cooled northbridge or something heat related.