Old and New RAM combination crashing system but memtest86+ shows no error

[amish]

Ok here is scenario:1) I am using this machine from 5-6 yrs2) Its P3 machine with 256MB RAM3) Two days back I bought additional 256MB RAMI did the following:1) I removed old RAM put new RAM2) Memtested it with memtest86+ boot CD, no errors.3) Then ran system. Which worked fine for abt 14hrs non-stop without problem, then I shut it down.Then I put old RAM back, so now total 512MB ram in system1) Memtested both together non-stop for abt 7hrs and it gave no errorBut then after I booted my system, it kept crashing within 2mins of boot.Then I went to BIOS and used "fail-safe options"Right now it hasnt crashed from abt 45mins. So I wanted to know,1) if anyone knows reason2) can u explain me in detail what cud be optimum option in BIOS?3) Does it depend on motherboard?4) ACPI was enabled earlier now disabled, so does that have any relation with RAM?5) ESCD was disabled but based on mini-help on BIOS, I thought I shud enable it, is it right? Also shud I disable it after booting once?My both RAM are 133MHz (printed on them) but right now its set to 100MHz in BIOS (fail-safe default),1) So I guess I lose some speed but not so noticeable, am i right?2) Is 100MHz safe and compatible option for 133MHz RAM? I am ready to sacrifice 33MHz if system stays stable as overall I still get faster system because of much less swapping.Both RAMs are from different companies.

 

[vishalrao]

i think you can keep it at 133 (unless the new RAM is not really 133 and incorrectly labeled/printed, but doubt it)... but in the BIOS there may be another option for RAM "CAS" timings like "5-3-3-3" or some such sequence of 4 numbers... try selecting the higher sequence of numbers (little slower) but at least you might be able to keep it at 133

 

[amish]

i think old and new RAM both worked individually on 133MHz. i fadely remember that it was 133 in bios earlier (not 100% sure). but both together crashed system.right now with "fail-safe" in bios (which puts RAM at 100MHz).. system is running from almost 5 and half hr.tomorrow i will try with ur suggestion. thanks.any1 has more inputs?

 

[amish]

i changed frequency to 133MHz and it didnt crash for 1hr yesterday..but today morning ... it crashed twice.. so i switched it back to 100MHz and hasnt crased fullday.so thats it, the update.

 

[vishalrao]

there was no "CAS" timing setting in the BIOS somewhere?

It may not be a single sequence, it may be 4 items like

Precharge time : 5
Cycle time : 3
Blah time: 3
Blah2 time: 3

You can put both RAMs at 133, just bump those 4 numbers to their highest settings...

For example: http://img.tomshardware.com/us/2006/01/04/bios_from_a_to_z/ram.jpg

See the 4 items at the top for DRAM timings (need to select manual)...

Another, see the first 4 number items: http://www.xbitlabs.com/images/mainboards/ga-8pe667ultra2/bios-mem.jpg

But if you dont want to play around, then its okay to leave it at 100 because theres not much speed difference in apps there...

 

[amish]

Yes values were there... all were already highest. I guess "fail-safe default options" already put them to maximum by default.I will try to put freq to 133MHz again but not today, some other day.

 

[viralbug]

maybe the different companies is causing a bit of problem.newer ddr2 rams generally dont face any such problems but in your case ddr rams might be giving problems. as long as its stable at 100 mhz theres nothing to worry about.have you checked the timings on both old and new ram? look on the label on the rams. the default ram timings on both might be different.

 

[amish]

yes its stable on 100MHz... abt settings on RAM, i didnt know abt timings and all. and now both RAM are in PC and just want to let them be there. but yes may be timings wud be different as one RAM is more than 5yrs old and different companies.but thanks i learnt few new things from u.as of now i am enjoying faster computing!