Can I use PC66 SDRAM in PC100 computer?

[GizmoFreak]

My computer takes PC100 SDRAM SODIMMS. Can I use PC66 RAM in there? Will anything bad happen? Will it be considerably slower?

I have 64MB of PC100 SDRAM in there but was thinking of putting in 256MB of PC66 SDRAM, which I came across.

Any help would be appreciated. Thanks.

 

[mrzed]

Depends on what your FSB is running at. If you are running at 100Mhz FSB, then no. What would happen is your computer would most likely refuse to boot.

 

[Sid59]

all your ram will then run on PC66 .. which sucks.

 

[GizmoFreak]

Not sure what the FSB is running at.

The computer is a Toshiba Satellite 2100CDT with 400mhz AMD K6-2 processor. Any idea what the FSB might be running at?


Isn't 256MB at 66mhz better than 64MB at 100mhz?


EDIT: Actually, I noticed the max memory is 192MB with the 64MB chip soldered.

 

[ISAslot]

The standard mem. in that laptop is 100mhz and the bus is up to 100mhz

 

[bendixG15]

I have been able to run some PC66 RAM at 100 and it passed memtest86.
Other pieces did not.
So it depends on the memory.

 

[Sid59]

Originally posted by: GizmoFreak
Not sure what the FSB is running at.

The computer is a Toshiba Satellite 2100CDT with 400mhz AMD K6-2 processor. Any idea what the FSB might be running at?


Isn't 256MB at 66mhz better than 64MB at 100mhz?


EDIT: Actually, I noticed the max memory is 192MB with the 64MB chip soldered.

prolly PC100 .. i have the Toshiba Satelleite 1605 and the 450 k6/2 and it runs PC100. Grab AIDA32 and it'll tell you all.

 

[GizmoFreak]

I think I'm going to scrap the PC66 idea. Thanks everyone for the input.

 

[Whitedog]

Originally posted by: Sid59
all your ram will then run on PC66 .. which sucks.

Uh, no. Not hardly.
It will try to run the mem at 100 and will probably not even boot up. You can't change the memory speeds on those old computers... You'll have to just get 128MB of either PC100 or PC133. No matter which kind you get, it will run at 100MHz.

 

[Blastman]

IN the old tests I've seen most PC66 memory will make it up to about 110mhz without a problem.

 

[Blastman]

I should add that some of the very first manufactured PC66 generic ?el-cheapo? brands may have trouble at 100mhz.but they would likely be 32MB and 64MB sticks, sounds like you have 128MB sticks. Also, the memory timings on a laptop chipset are probably not that fast, so offhand I would think it should run no problem.

ADD: There will be no speed difference between PC66 and PC100 --- if they are both running at the same speed.

 

[Whitedog]

Originally posted by: Blastman
ADD: There will be no speed difference between PC66 and PC100 --- if they are both running at the same speed.

Say that again??? Hmmm... 66MHz and 100MHz is the same speed? Uhm, OK.

 

[Chaotic42]

Originally posted by: Whitedog

Originally posted by: Blastman
ADD: There will be no speed difference between PC66 and PC100 --- if they are both running at the same speed.

Say that again??? Hmmm... 66MHz and 100MHz is the same speed? Uhm, OK.

I think he means if the PC66 is overclocked to PC100 speeds.

 

[Blastman]

Originally posted by: Whitedog

Originally posted by: Blastman
ADD: There will be no speed difference between PC66 and PC100 --- if they are both running at the same speed.

Say that again??? Hmmm... 66MHz and 100MHz is the same speed? Uhm, OK.

Yes, if you run ...

PC66 at 100mhz and
PC100 at 100mhz ...

they will both be providing the same fsb/memory bandwidth. Hence no performance difference. The PC100 may be capable of running faster timings than the PC66, but that is a different matter.

 

[nightowl]

Most PC66 DIMMs are rated at 10ns which equates to 100MHz. So, they should work at 100MHz. Now, some may have low quality chips or PCBs that do not allow them to operate at that frequency or some may not work because the motherboard detects the SPD settings on the chip and prevents the "overclocking" of the chip. If you have the memory, try it. It is not going to hurt anything.

 

[GizmoFreak]

Yeah, it's a 128MB Module. Samsung branded I believe.

How do you overclock memory? Does this being a laptop complicate things?

EDITED for grammar

 

[alkemyst]

yes and no.

It depends on the chips.

If the memory is older than the PC100 spec then it may be able too.

Same with a lot of highend PC100 memory is able to run PC133 better than some PC133.