SDRAM? What is it?

[CmdrJeffSinclair]

I already understand the difference between DDR-DDR4 as well as GDDR....but from what I've read SDRAM is simply synchronized dynamic random access memory....how the hell does that make any sense!!

Three words that should never be linked into one sentence...
1) Synchronized, as in made uniform
2) Dynamic, as in variable but not random
3) Random, as in non-sequential or ordered
.....this entire name makes no sense.

I see 16GB of G.Skill 3200MHz SDRAM and I wonder why it's $300 cheaper than plain DDR4 RAM. I did my best to read up, so probably a VERY basic explanation will sort of what I find confusing.

What is SDRAM and how is it different from plain RAM?

Thanks!

 

[Dunlop0078]

Straight out of the A+ textbook.

DIMMs use a 64-bit data path. (Some early DIMMs had a 128-bit data path, but they’re
now obsolete.) A DIMM (dual inline memory module) gets its name because it has independent
pins on opposite sides of the module.
Early DIMMs did not run in sync with the system clock because they were too slow to
keep up. Their speeds are measured in nanoseconds (ns), which is how long it takes for the
module to read or write data. The fi rst DIMM to run synchronized with the system clock
was synchronous DRAM (SDRAM), which has two notches, and uses 168 pins. (Don’t
confuse SDRAM with SRAM. SRAM is static RAM used in processor memory caches, and
SDRAM is dynamic RAM used on DIMMs.) Synchronized memory runs in step with the
processor and system clock, and its speeds are measured just as processor and bus speeds
are measured in MHz.
Double Data Rate SDRAM (DDR SDRAM, or SDRAM II, or simply DDR) is an
improved version of SDRAM. DDR runs twice as fast as regular SDRAM, has one notch,
and uses 184 pins. Instead of processing data for each beat of the system clock, as regular
SDRAM does, it processes data when the beat rises and again when it falls, doubling the
data rate of memory. If a motherboard runs at 200 MHz, DDR memory runs at 400 MHz.
Two other improvements over DDR are DDR2 and DDR3. DDR2 is faster and uses less
power than DDR. DDR3 is faster and uses less power than DDR2. Both DDR2 and DDR3
use 240 pins, although their notches are not in the same position. They are not compatible,
and the different notch positions keep someone from installing a DDR2 or DDR3 DIMM in
the wrong memory slot.
Factors that affect the capacity, features, and performance of DIMMs include the number
of channels they use, how much RAM is on one DIMM, the speed, error-checking abilities,
and buffering. All these factors are discussed next.

 

[CmdrJeffSinclair]

Straight out of the A+ textbook.

DIMMs use a 64-bit data path. (Some early DIMMs had a 128-bit data path, but they’re
now obsolete.) A DIMM (dual inline memory module) gets its name because it has independent
pins on opposite sides of the module.
Early DIMMs did not run in sync with the system clock because they were too slow to
keep up. Their speeds are measured in nanoseconds (ns), which is how long it takes for the
module to read or write data. The fi rst DIMM to run synchronized with the system clock
was synchronous DRAM (SDRAM), which has two notches, and uses 168 pins. (Don’t
confuse SDRAM with SRAM. SRAM is static RAM used in processor memory caches, and
SDRAM is dynamic RAM used on DIMMs.) Synchronized memory runs in step with the
processor and system clock, and its speeds are measured just as processor and bus speeds
are measured in MHz.
Double Data Rate SDRAM (DDR SDRAM, or SDRAM II, or simply DDR) is an
improved version of SDRAM. DDR runs twice as fast as regular SDRAM, has one notch,
and uses 184 pins. Instead of processing data for each beat of the system clock, as regular
SDRAM does, it processes data when the beat rises and again when it falls, doubling the
data rate of memory. If a motherboard runs at 200 MHz, DDR memory runs at 400 MHz.
Two other improvements over DDR are DDR2 and DDR3. DDR2 is faster and uses less
power than DDR. DDR3 is faster and uses less power than DDR2. Both DDR2 and DDR3
use 240 pins, although their notches are not in the same position. They are not compatible,
and the different notch positions keep someone from installing a DDR2 or DDR3 DIMM in
the wrong memory slot.
Factors that affect the capacity, features, and performance of DIMMs include the number
of channels they use, how much RAM is on one DIMM, the speed, error-checking abilities,
and buffering. All these factors are discussed next.

It was block paragraphs like that which only confused me more man.

Just summarize SDRAM for me in 3 sentences if you can. Thankfully I at least understand DDR and DIMMS and all of that.

 

[CmdrJeffSinclair]

so SDRAM is dynamic RAM used on DIMMs.) Synchronized memory runs in step with the
processor and system clock, and its speeds are measured just as processor and bus speeds
are measured in MHz.

What does this mean...it's limited by CPU clock? Or throttled by the clock? Does this mean that a super fast processor is better with SDRAM but a slower processor would not do well with it? I understand the random aspects of RAM, but SDRAM seems to be contradictory

 

[Dunlop0078]

Double Data Rate SDRAM (DDR SDRAM, or SDRAM II, or simply DDR) is an
improved version of SDRAM. DDR runs twice as fast as regular SDRAM, has one notch,
and uses 184 pins. SDRAM is old and slow and wont fit into any modern motherboard.

 

[CmdrJeffSinclair]

Double Data Rate SDRAM (DDR SDRAM, or SDRAM II, or simply DDR) is an
improved version of SDRAM. DDR runs twice as fast as regular SDRAM, has one notch,
and uses 184 pins. SDRAM is old and slow and wont fit into any modern motherboard.

but the RAM I'm looking at is G.SKILL Ripjaws 4 series 16GB (4 x 4GB) 288-Pin DDR4 SDRAM 3200 (PC4-25600) Desktop Memory Model F4-3200C16Q-16GRKD

link here on amazon http://www.amazon.com/G-SKILL-Ripjaws-288-Pin-PC4-25600-F4-3200C16Q-16GRKD/dp/B00NO5CLXM/ref=sr_1_1?ie=UTF8&qid=1424295825&sr=8-1&keywords=ddr4+3200

Clearly it says SDRAM 288 pins so it's for the x99 mobo

 

[CmdrJeffSinclair]

nevermind, I found the answer on wiki finally

n computing, DDR4 SDRAM, an abbreviation for double data rate fourth generation synchronous dynamic random-access memory, is a type of synchronous dynamic random-access memory (SDRAM) with a high bandwidth ("double data rate") interface. Released to the market in 2014,[2][3][4] it is one of the latest variants of dynamic random access memory (DRAM), some of which have been in use since the early 1970s,[5] and a higher-speed successor to the DDR2 and DDR3 technologies. It is not compatible with any earlier type of random access memory (RAM) due to different signaling voltages, physical interface and other factors.

DDR4 SDRAM was released to the public market in Q2 2014 with a focus on ECC memory,[6] and an anticipated launch for non-ECC modules in Q3 2014.[7]

 

[CmdrJeffSinclair]

that last sentence made it all clear...focuses on ECC memory.

 

[Dunlop0078]

Double Data Rate SDRAM (DDR SDRAM, or SDRAM II, or simply DDR) is an
improved version of SDRAM. DDR runs twice as fast as regular SDRAM, has one notch,
and uses 184 pins. SDRAM is old and slow and wont fit into any modern motherboard.

but the RAM I'm looking at is G.SKILL Ripjaws 4 series 16GB (4 x 4GB) 288-Pin DDR4 SDRAM 3200 (PC4-25600) Desktop Memory Model F4-3200C16Q-16GRKD

link here on amazon http://www.amazon.com/G-SKILL-Ripjaws-288-Pin-PC4-25600-F4-3200C16Q-16GRKD/dp/B00NO5CLXM/ref=sr_1_1?ie=UTF8&qid=1424295825&sr=8-1&keywords=ddr4+3200

Clearly it says SDRAM 288 pins so it's for the x99 mobo

That is DDR SDRAM not SDRAM there two different things. That ram should be fine. Post the links to the more expensive ram you were talking about.

 

[Dunlop0078]

Yah you dont need ECC ram thats for servers.

 

[Pinhedd]

I already understand the difference between DDR-DDR4 as well as GDDR....but from what I've read SDRAM is simply synchronized dynamic random access memory....how the hell does that make any sense!!

Three words that should never be linked into one sentence...
1) Synchronized, as in made uniform
2) Dynamic, as in variable but not random
3) Random, as in non-sequential or ordered
.....this entire name makes no sense.

I see 16GB of G.Skill 3200MHz SDRAM and I wonder why it's $300 cheaper than plain DDR4 RAM. I did my best to read up, so probably a VERY basic explanation will sort of what I find confusing.

What is SDRAM and how is it different from plain RAM?

Thanks!

1. Synchronized means that the device samples all input signals and drives all output signals with respect to a synchronizing signal. That synchronizing signal is the clock signal. An asynchronous device does not have a clock signal, and thus responds to changes in input immediately. If you look at an SDRAM data sheet, you'll notice that all primary and secondary timings are expressed in nanoseconds, and that each timing is a scalar multiple of the clock period.

2. Dynamic means that the memory is stored using dynamic logic rather than static logic.

3. Fun fact, SDRAM does not allow for true random access like SSRAM does. Truly random access implies that the time needed to perform an operation on some memory element at an arbitrary location X is the same as the time needed to perform that same operation on some other memory element at an arbitrary location Y where X and Y are disjoint.

For a more detailed explanation, please read my memory tutorial at the top of the forum