Mixing rams - want your feedback



hey guys, sorry i havent been around much but i been away on break

I got a Q and want some responses prior to experimenting, cause last time i did windows crapped out and i had to do a full format and restore

Basically, I got a XP1500+ AMD running at 233FSB on an MSI systemboard. I want to pop in two sticks of 512mb ram but they are rated for 333FSB, I know most of the time RAM will clock down or sometimes just not go at all, but in a recent experience about a year ago I had one piece rated for higher than the CPU and board and ran fine for 2 weeks till it just cause a serious PC crash which led me to do more work.

Anyone here this will do OK or should I avoid this combination?


simple, just install the ram then go into the bios and set the ram to 133 FSB (which is what your cpu should be running at) then you can probably tighten the timings slightly seeing as its rated for 166/333 FSB, for that get a prog called CpuZ it should tell you what timings and speed your memory is capable of running at.


If I were you (after the previous trouble) I would try and get hold of some matching RAM (I just got some PC2100 for my comp). By the look of it, it’s just not worth the trouble.


Unless you go for some odd brand there shouldn’t be any issues, at least with Hynix, Crucial, Kingston, Corsair.


RAM is a pull from a Dell Optiplex GX270, brand name of RAM is “Promos”, its two identicle mods of 512MB DDR 333MHz CL2.5 PC2700 and I am gonna throw them into a board meant to receive PC2100 at 266MHz, the board is this one: KT2 Combo-L

I also intend to increase the CPU from a 1500 XP to a 2800 XP which runs at 266MHz. I am just wondering if this RAM will even clock down at all. I do have a 512MB mod meant to run at 266MHz PC2100 but I don’t wanna mix and I would rather have a gig than half of a gig.


Can you identify the part #.



if the two sticks are exactly the same you should be fine…just avoid mixing sticks with different ICs…



that’s it, does that info help much to know if it will crash and hang on me?

I am just trying to be extra cautious because last time the PC appeared to work well for about two weeks then it just had a BSOD with a memory dump related stop code.


Memtest86. Run it from floppy overnight and if there’s no errors then you’re good to go. the RAM should work great, and you could even play with timings a bit at the lower speed.


wow, nice prediciton, it is exactly what my next step is to be, I guess I will let you guys know how it all turns out.


Most ram will run fine @ lower frequencies, but you might have to tighten up the timings. For instance, my ram is PC 3200 (400 MHZ), and I have it running @ 330MHZ (just shy of PC 2700). The timings on my ram are supposed to be 2-3-3-7 @ 333 MHZ and 2.5-3-3-8 @ 400 MHZ. Most ram have specs like that so you can run them @ multiple frequencies. If you run into stability problems, you can tinker with the timings and voltage. Usually, a nudge in voltage will do wonders like it did for my ram. I gave it some voltage, and tightened up the timings to 2-2-2-5 with 2.7v :iagree: . You can probably run that ram @ 266 MHZ just fine, the SPD timings might not work though. Test to see if it’s stable with memtest (bootable floppy version), or it might give you BSODs and stuff. If it’s not stable, try tinkering with the timings. Try setting them to the PC 2700 settings of 2.5-3-3-7, and see if the errors go away. If the mobo has voltage options, try tightening up the timings, and giving them a little extra juice. I bet you can get 2-3-3-6 timings with 2.6v, and MAYBE 2-2-2-5 with 2.7v. Don’t go over 2.7 with no heat spreaders, some ram gets HOT if you do that. My ram does get a little warm with 2.7v going through it, but I have LOTS of airflow through my case. Good luck, that should work OK. :iagree:


Unless you have some POS RAM on your hands there’s no issues at all mixing PC2100 with PC2700 or even PC3200 and still running all @ PC2100. I do recommend you to set RAM frequency manually though otherwise you might get some issues such as trying to run all @ PC2700 etc.