PC133 RAM in PC100 board?

[ablang]

Is it possible to install PC133 SDRAM in a motherboard that specifies PC100?

I'm just wondering if I can buy faster RAM to put in my brother's old computer, and have the RAM drop down to PC100 to match his existing PC100 SDRAM memory.

[Roy]

Absolutely! I'm surprised they're even selling PC100 anymore. They should be giving it away just to clear the shelves!

Of course, there are a few boards out there that are picky about RAM, but it has nothing to do with the speed spec.

[Fingers]

Sorry to hear that Bovon, but I believe you are the very small exception to the rule.

ablang, use the Memory Locator at Crucial.com to verify what type of memory you can use. Unless your mobo uses the Via MVP3 chipset (like Bovon's VA 503+ does) I wouldn't give a second thought about getting PC133... even then, I still would probably go with the PC133.

<A HREF="http://support.crucial.com/scripts/crucial.exe/solution?11=001018-0005&130=000971881883&14=&2715=&15=&2716=&57=faq&5 8=&2900=&25=-1" TARGET=_blank>Can I use a 128MB PC100 SDRAM DIMM with a 128MB PC133 SDRAM DIMM?

Generally you can mix PC100 and PC133 memory in the same system. The faster memory will run at the slower memory's speed (in this case PC100). However, there are some systems that will not correctly run this memory configuration. It is rare, but we suggest you contact your computer manufacturer or motherboard manual for specifics.</A> - Crucial FAQ

<A HREF="http://support.crucial.com/scripts/crucial.exe/solution?11=991227-0001&130=000946320597&14=&2715=&15=&2716=&57=searc h&58=&2900=&25=6&3=pc133" TARGET=_blank>Can I use PC133 or PC100 SDRAM in my 66MHz PC?
</A>

Should I buy a PC100 module or a PC133 module?




[This message has been edited by Fingers (edited 05-05-2001).]

[Fingers]

Bovon, I believe you can find the answer to your dilema in FAQ for the VA 503+

...PC-133 memory with CL=2 will definitely bring a beep code and no screen at POST with most FIC socket 7 board such as VA-503+, PA-2013, PAG-2130, VA-503A...

[This message has been edited by Fingers (edited 05-05-2001).]

[Bovon]

Bro Fingers, thanks so much for your reply.

I did write First International Computer (FIC), before ordering the ram. I posted a general question at Corsair's website, and emailed Crucial prior to ordering the ram. The general consensus was that the pc 133 would/should work, but it was unknown to them if it actually would, due to my particular mobo not having been tested.

Two weeks!!...after ordering, and one week after recieving the ram, I FINALLY!! recieved an answer from FIC, that my board would not work with pc 133 modules...Thanks a **** bunch!!

As I said initally, this isn't anything for me to loose any sleep over, because when I get my new board here, the ram will work fine. It just erks the life out of me that a simple question to a board manufacturer will either go unanswered, or a two-three (or more) week period passes before they see fit to answer.

Anyways, the pc133 ram will most probably will work just fine in most RECENT mobos, just be aware, that it may not. Investigate as much as possible first. As in my case, the ram will be used..it will not be something I will have to eat...others looking to upgrade, may not be quite as fortunate as I happen to be.

[Mark]

Bovon,

Try the stick in the second or third dimm slot. That's the only way I could get my 503+ to stop beeping when I use PC133 ram, 128mb Infineon by the way. But only one gets recognized when I install two of them. Go figure. My prayers go out to anyone with a VA503+ board. Absolutely the most obnoxious board I have ever dealt with. Anyone aspiring to A+ Certification should buy one of these to use as a hands on trainer.

Fingers,

Judging by some of the posts I've been reading here it seems like this problem is fairly widespread. I've got the same problem with my Asus P3B-F which uses the Intel BX chipset. Generally regarded as a rock solid board it just doesn't work well with PC133. I can use one stick either by itself or mixed with certain others(PC100 & PC133) and it works fine. But it can't handle just two of the same size and type. I've tried every memory setting in the bios and couldn't sort it out. I've also played musical dimm slots. A couple of friends are having an even worse time. The crazy thing is, as long as I mix the sizes and types together, the SS7 VIA boards do a better job of solving incompatibilities between the dimms.

It appears that there's something new in the way PC133 is designed or manufactured that makes it not 100% backward compatible. But, in my ignorance I don't know what it is or how to fix it. All I can say is that in seven years I've never heard of or experienced the number of memory problems that are showing up now.

As a side note my friends and I do a lot of photo manipulation and scanning and we use the memory test from Norton Utilities to predict system crashing memory incompatibilities. If it fails Norton we swap, remove and retest dimms until it passes or else we're garanteed to experience a crash.

Maybe somebody has the answer.

[Bovon]

Hold on a minute...

I thought the same, and It COULD be a bios upgrade issue with my mobo.

I have an older FIC VA 503+ board. I did a lot of questioning around before ordering some pc133 ram. All of the replies said..."sure, go ahead, ram is backwards compatable".

Well, I'm here to tell you that altho ram may be backwards compatable, the mobo chipsets/bios apparently are not fowards compatable.

I ordered a module of 256 mb pc 133 cas 2, and two modules of pc 133 128 mb cas2 Crucial. Installed, I had crashes and lockups from the beginning. Finally, I had to reinstall the original 128 mb pc 100 ram, and all is normal again. (I installed the Crucial one module at a time...1 module of 256 mb, 2 modules of 128 mb, 1 module of 128 mb, ect.)

All of these tests were made at bios defaults, and tweaked as well...nothing worked...two weeks were spent evaluating the system.

As I said, a bios upgrade may have fixed this, but sence I actually ordered the Crucial for a future upgrade, I decided to let the bios upgrade go...

[Bovon]

I tried 1 stick of Crucial 256 pc133, I tried 1 stick of 128 mb pc133, I tried 2 sticks of 128 mb pc133. The only thing I didn't try was, different slots. I never had a problem booting...just lockups, and BSODs A LOT!!. SiSoft Sandra gave me worse results than the pc100 did, and I tried every tweak I have available in this old, original bios.

I didn't think to run Norton of the modules...that may have told me something

[Peter M]

Problem's not so much in the speed grade, it's in SDRAM density per chip.

Aging chipsets, like Intel BX and 810, VIA's non-133-MHz chipsets, and older SiS and ALi chipsets as well, cannot handle SDRAM density beyond 128-MBit (bit!) per chip properly.

Now on today's el-cheapo PC133 DIMMs, you are very likely to get higher density SDRAM - higher density means fewer parts, and fewer parts means lower cost. PC100 DIMMs possibly are older stock with a higher probability of being made from older SDRAMs.

So if you want to make sure you get a DIMM that's compatible with those old chipset, then your 128-MByte DIMM must be made from 8 chips 8 bits wide each (to get 128-MBit technology chips), and your 256-MByte DIMM must be 16x8 not 32x4 or even 32x8.

Regards, Peter

[Mark]

Thanks, Peter! That was just the answer I was looking for! Can you explain in more depth about the bit width and how to ID a DIMM that I can use with my board? My friend and I are going to do some shopping tomorrow to eliminate this problem and I want to make sure I buy the right stuff.

Bovon, I partially lied. It seems that when I went to boot up the 503+ it just beeped and I had to remove the battery and wait 20 minutes. I guess it was a short lived romance with the Infineon. I tried some other sticks and it's working normal again.

I also lied about trying every setting in my Asus P3B-F bios. I never went to the 10ns clock setting because the ram chips are marked 7.5ns and I thought going higher than 8ns was senseless. That was until I downloaded the datasheet and read that those same chips in a PC100 stick are designed to run at 2-2-2-6, but in a PC133 stick they run at 3-3-3-10!!! I set the appropriate values in the bios and even though Norton still doesn't like it I can now do anything I want and the system remains crash free although slower.

[cheapster]

I have to join in and relate a similar experience with a stick of Kingston Valueram (128 MB PC-133) and a Soyo SY7-IWM/L motherboard (intel 810 chipset). The system was running great with a 128 MB stick of generic PC-100 ram, but I thought I should just throw in this Kingston PC-133 just so I could use the 256 total. To make a long story short, the PC-133 would not work at all! Not with the PC-100, not by itself, not in any of the slots. I was stunned. It is working fine in my MSI-6309 alongside a pair of Mushkin Infinion sticks and running cas2 at 124 MHz. But it would NOT work at all in the Soyo. So be careful making the blanket statement, of course it is backwards compatible. It depends!
Chuck
PS My Soyo is running at 66 Mhz fsb, should that make any difference?

[Mark]

Peter,

I guess I don't understand how to ID an 8 bit chip. The ones I have problems with are PC133 128mb, 8 chips of 16mb each(states 16Mx64 SDRAM on the label). Others I have that work OK are PC100 32mb, 16 chips of 2mb each(referred to as 16x32?) and a PC133 64mb, 8 chips of 8mb each(states 8*64 on the label). I don't know what makes one 8 bit and the other not.

[digidave]

Have a soyo socket seven mb sy-5ema+ running 128mb of pny brand pc133memory,no problems whatso ever,formerly had 64m of generic pc100,machine runs solid,no problems,

[Peter M]

Mark, so it boils down to your board not handling 128-MBit technology SDRAM. Those of your DIMMs that have 64 MBits per chip (64-MByte 8-chip and 128-MByte 16-chip) work fine, and those that have 128 MBits per chip (128-MByte 8-chip) don't, even though these chips are 8-bit wide for sure (else 8 of them couldn't form the required 64-bit width a DIMM must have).

Now VIA MVP3 technically can handle 128-MBit technology, I've seen it on Epox and PC-Chips boards. See if there's a BIOS update for your 503+ board.

Regards, Peter

[Mark]

Peter,

Thanks for the info. I bought four 128mb PC133 sticks with Mars memory on them. I specifically looked for ones with 16 chips on them but I don't think they're readily available. More than likely a cost issue as you stated previously. These sticks had 12, yes 12, chips on each one. They don't pass the Norton test but they do run stably at 2-2-2-8 with fast timing. I can now scan a 400mb file with no problems. Hopefully, they'll work as well with any board I buy in the future.

digidave,

It was just the Infineon memory that was giving me trouble, I guess because of the density. I've got a mixture of 64mb PC100 and PC133 sticks that're running just fine. The only other time I saw anything like this was when I had a stick of generic PC66 that would run at 112mhz but name brand PC100 would not work at 100mhz in the same board.

Mark