quick pc memory question

Is it ok to run pc133 dimm in a 100 megahertz bus speed (P4-650) system? Will the memory run ok at the slower speed? Reason I ask is that I have to pick up a stick today and pc133 is more readily and cheaper available to me.

Yes, it'll usually work fine but there is one thing you need to watch out for-the size of the new memory stick. Most 256 MB sticks nowadays are single-sided (i.e. memory chips are only on one side of the stick). Many older motherboards, such as the AX6B in my machine, can only accept up to 256 MB per memory slot, and require double-sided memory in order to reach that capacity. Single-sided memory may not work at all, or usually it will but it will only be recognized as 128 MB. Ditto for motherboards which support up to 512 MB per slot. The single-sided 256 MB sticks will work fine, as will the double-sided 512 MB ones. However, the newest single-sided 512 MB sticks will either not work, or be recognized as 256 MB. If you have the manual for your motherboard it will usually tell you the maximum supported memory capacity and the maximum per slot. Armed with that info, you can then pick memory which will work. In general faster RAM will always work at a slower speed, but the mismatch in densities is what led to the myth that PC133 won't work in a PC100 motherboard.

Exc response.

Oh man this doesn't sound good. I did some research and it is a Biostar M6TBA MB. It has three slots that can only hold 128MB per and two are filled already. It is to be converted into an XP machine so I'm hoping if I fill the last slot with a 128mb stick then 384mb total will be enough to run xp. I have a powerleap upgrade processor installed that is supposed to be a Celeron 1.4Ghz. The machine will only be used for home apps and internetting, not gaming, so I think the CPU is ok (ran win98 fine) but now I'm really worried about the memory as I think you need at least 512MB to really run XP sufficiently, don't you?

xp runs fine under 384. been there done that. the fact that it's at 100mhz is what's gonna make it seem slow. make sure you have a faster HD on that PC. it sounds like it may have a 5400 RPM drive. get a 7200rpm western digital. the 40gb western digitals are nice and fast. much faster than the 200gb ones. i've had many problems with maxtors dying on me. i keep away from them. hitachi is good as well.

Leon

Hi Leon, thanks again for the response. It is a 7200rpm drive but only 2 mb cache and yes it is a Maxtor. It was a Staples deal at the time I bought it. There also is a ultradma66 sig pci controller as the mb does not support it. I'm wondering if I'll be able to reformat drive and install xp with drive attached to sig controller or will I have to hook back up to mb and then move cable to sig controller once xp is installed and card is recognized?

I've had equal bad luck with Maxtor's and WD dying on me but the customer service for both has been ok. In this case the drive is already a year old so no longer in warranty but has held up fine so far.

if your bios supports booting from other methods than the primary and secondary ide controllers, floppy, and CD-ROM, you should be able to do it without moving anything. most of the time if it doesnt work you can flash your bios with a version that supports it.

Leon

Well I've pretty much decided to say "frig it" rather then play games with exisiting hardware. This is for my dad, BTW, who does not play games, mostly does home apps and web surfing. I went to a local computer shop that I have done business with in the past. For a little less then $300, I can get a Asus ATV400-MX "all in one" mb, a AMD Sempron 2500+, 512MB of mem and a typical computer shop case although it has a nice side window with a lighted fan. I realize I could probably do better on the Internet but I think the prices are pretty good for a mom and pop shop and I need to cobble something together this weekend. I can use the other existing hardware from the old machine. I'll have to do some research on the mb, however. I never bought one as cheap as this one at $75 but it is an Asus. The only other all in one mb I tried had noisy audio but if this is the case, I can use the existing SB live.

btw, i think the motherboard is "A7V400-MX" not "ATV400-MX"

Nothing like trying to turn a sows ear into a silk purse...