Single sided versus double sided RAM modules

Although you posed a technical question, this is a not so technical answer. Searched a lot today and finally found something pertinent using dogpile.

According to this page the reason may be that each rank, side, row is addressed by a single Chip-Select pulse, so two rows need 2 pulses (twice the time). Check the bottom of the page under "Definition of Memory Module Terms ".

Suspect no impact, assuming it's still good, but try it and see (at your own risk, of course). Have never shunned mixing brands without a single problem.

But probably not a significant difference.

 

Hello Christer,

I think you have probably answered your own question.

When speed is mentioned it generally refers to frequency. If you overclock the RAM it will go faster (also, create heat and risk failure). The CAS Latency is next most important (the figures 3.0-3-3-6 after the frequency). The CAS Latency is an internal speed like the refresh rate as you have found, but more important to how well the RAM works. High quality RAM will have a lower CAS Latency than low quality RAM.

AMD and Intel now have different ways of utilising RAM...DDR or DDR2. You will not be able to compare those because they use different systems.

I have not researched much more.

I don't research RAM sticks any more, there are too many variables like the double-sided "difference ". I just put it in and see if it works. The only hazard I know of is to put/force a RAM stick of the wrong voltage into a slot. Early 168 pin SDRAM had lugs/grooves that were only slightly different to later sticks of a different voltage. It was/is possible to force the stick into the wrong slot with enough force. Check if the lugs/grooves match by putting the two sticks edge to edge with one reversed to the other.

Apart from that...the motherboard may "like" it or it doesn't.

Matt
ps ARRRGGH you got me into the discussion!


pps EDO or non-EDO is important, the motherboard specs will tell you which type is compatible, won't hurt to try.

ppps(?) The "comparitors" at the RAM manufacturer's website will have a recommendation for which best/acceptable/works type of RAM is best (works?) with a particular motherboard.

pppps ARRRRGGH

 

Had to Jump In to wish you guys a Merry Christmas. You picked a setting that I know little about but in this case, lower isn't neccessarily better.

This from the Master (and that ain't me).

Refresh Rates - Common Options: 7.8 µsec, 15.6 µsec, 31.2 µsec, 64 µsec, 128 µsec, Auto

This BIOS feature allows you to set the refresh interval of the memory chips. There are three different settings as well as an Auto option. If the Auto option is selected, the BIOS will query the memory modules' SPD chips and use the lowest setting found for maximum compatibility.
For better performance, you should consider increasing the Refresh Interval from the default values (15.6 µsec for 128Mbit or smaller memory chips and 7.8 µsec for 256Mbit or larger memory chips) up to 128 µsec. Please note that if you increase the Refresh Interval too much, the memory cells may lose their contents.

Therefore, you should start with small increases in the Refresh Interval and test your system after each hike before increasing it further. If you face stability problems upon increasing the refresh interval, reduce the refresh interval step by step until the system is stable.

 

I thought this topic sounded like Rockster2U bait

Merry Xmas to you as well, hope things are going well.

Christer, don't stop "digging" on my account. RAM research drove me crazy when I started, mainly due to the fact that there were so many different types and there was little or no information about individual models. The industry is standardizing a lot of things now so it will be easier to at least find out some information.

I cannot add much more, but I am interested to read your findings.

Matt

 

Perhaps this explains it a little better and satisfies that inquiring (gotta love it) mind. Again, from the Master's own words:

Memory cells normally need to be refreshed every 64 msec. However, simultaneously refreshing all the rows in a typical memory chip will cause a big surge in power requirements. In addition, a simultaneous refresh causes all data requests to stall, which greatly impacts performance.

To avoid both problems, refreshes are normally staggered according to the number of rows. Since a typical memory chip contains 4096 rows, the memory controller usually refreshes a different row every 15.6 µsec (64,000 µsec / 4096 rows = 15.6 µsec). This reduces the amount of current used during each refresh and it allows data to be accessed from rows that are not being refreshed.

Usually, memory modules that use 128Mbit or smaller memory chips have 4096 rows while memory chips with higher capacity (256Mbit and above) will have 8192 rows. For memory chips that come with 8192 rows, the refresh interval will need to be halved to 7.8 µsec because there are now twice as many rows to serviced within the stipulated 64 msec for the entire chip.

Therefore, the typical refresh interval for 128Mbit (not MB!) or smaller memory chips would be 15.6 µsec while those for 256Mbit or larger memory chips would be 7.8 µsec. Please note that if you are using a mix of 128Mbit and 256Mbit memory modules, the fail-safe Refresh Interval would be 7.8 µsec, not 15.6 µsec.

Although JEDEC standards call for a 64 msec refresh cycle, memory chips these days can actually hold data for longer than that. So, using a longer refresh cycle is quite possible. With a longer refresh cycle, the memory chips are refreshed less often, reducing both the amount of bandwidth wasted on refreshes and the amount of power consumed (which is great for laptops and other portable devices).

 

This has been a fascinating discussion, nothing to add technically, just wanted to say Merry Christmass Guys!

And welcome back Rock Its been a long time.

Regards - Charles

 

Adrian Wong - third year medical student from Malaysia. Has authored the best BIOS Guide available anywhere at any cost in my opinion. His site is Adrian's Rojak Pot - named after a mixture of local Malaysian foods. There is a free version and as of about 3 years ago, he started a paid subscription version which covers subjects unavailable anywhere else on the Internet. (At least I've never found them anywhere else) He gets my contribution every year.

Charles - leave it to Chister to come up with a topic like this, huh? It grabbed my interest too and I have to admit, I didn't know much about refresh intervals either.