shanenin Posted March 24, 2006 Report Share Posted March 24, 2006 I would like to buy some memory off ebay. It would be nice to have some on hand for computer jobs. If I buy pc 133 sdram, will this work in systems that use pc 100 or pc 66? Quote Link to post Share on other sites
Dragon Posted March 24, 2006 Report Share Posted March 24, 2006 hi shanenin,no the backwards compatibility didn't exist until computers started using pc2100 and pc2700 ram. pc100, pc133, and pc66 ram are actually different sizes by a few millimeters. to the human eye it doesn't look like much, but when it comes to computers that is the same as trying to put a AAA battery in a spot designed for a AA battery. loose enough that things just won't work. Quote Link to post Share on other sites
shanenin Posted March 24, 2006 Author Report Share Posted March 24, 2006 thanks, I appreciate the input :-) Quote Link to post Share on other sites
Honda_Boy Posted March 24, 2006 Report Share Posted March 24, 2006 woah hold up. I've used PC133 RAM in PC100 slots just fine. I've even used PC 133 in PC 66 slots and it worked fine. It just didn't recognize all 64MB. I tonly saw 32MB. It was a 233MHz K6. Quote Link to post Share on other sites
MrBill Posted March 24, 2006 Report Share Posted March 24, 2006 hi shanenin,no the backwards compatibility didn't exist until computers started using pc2100 and pc2700 ram. pc100, pc133, and pc66 ram are actually different sizes by a few millimeters. to the human eye it doesn't look like much, but when it comes to computers that is the same as trying to put a AAA battery in a spot designed for a AA battery. loose enough that things just won't work.I have used many a stick of 133 in a 100 and not the first problem. Most 133 is backward compatible to 100. It does see the whole amount on the stick. I have use 128 and 256 with no problems at all. I just added the stick and have even tried switching the positions and it didn't matter. Go for it. Quote Link to post Share on other sites
Dragon Posted March 24, 2006 Report Share Posted March 24, 2006 most of the mobos that use that ram don't recognize the reverse compatibility. There were only 4 mobo manufacturers that actually utilized that process, and most of the time they didnt' give the entire ram usage or they heated the chips up to meltdown. Thats why it's classified and a no for reverse compatibility. more risk for damage on those machines than there is for these newer mobos that use pc2100 and up. Quote Link to post Share on other sites
TheTerrorist_75 Posted March 24, 2006 Report Share Posted March 24, 2006 Some manufacturers made combination PC100/133 that was compatible with either. Many of the early motherboards were finicky with memory. I have a Shuttle AI-61 Slot A board that will only use PC100. With this old memory you are better to order it as needed. No sense is spending money for stocked supplies that may only work in limited boards. Also remember many of the old Gateways, Dell and etc. needed specific type memory. Quote Link to post Share on other sites
shanenin Posted March 24, 2006 Author Report Share Posted March 24, 2006 all this information is really helpful. Thanks. Quote Link to post Share on other sites
TheTerrorist_75 Posted March 24, 2006 Report Share Posted March 24, 2006 I was just at another forum and someone bought PC133 at ebay and was sent unmatched unknown brands that were not even compatible with each other. One stick worked in his board and the other didn't. You have to watch out for this at ebay. Some sellers just pull out memory from different PCs and toss them in a box. When you order they just grab the number of sticks ordered without matching them. This is especially bad when wanting the memory for proprietary PCs. Quote Link to post Share on other sites
shanenin Posted March 24, 2006 Author Report Share Posted March 24, 2006 memory upgrades can be a big pain in the a%#. You can get all of the numbers to match the specs and still run into problems. Quote Link to post Share on other sites
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