DDR2 RAM. I JUST CANT GET MY HEAD AROUNT IT? 1

[ckes101]

Hi Guys and thanks for looking at my thread. Have you ever had a problem that every body else seems to grasp yet you just cant seem to get it. Well i have and here it is. With old DDR ram if i built a system lets say with a CPU P4/2.8/533 i new i would use PC2700(DDR333) but i could also use PC3200(DDR400) as the ram would Just run at the slower speed. Now here is where I'm losing the plot..Does DDR2 work in the same way?? i have an ECS 662/1066T-M2 mobo which i am using DDR2 667(5300) now i have a friend who is willing to give me his old 2 gig of DDR 800 (PC6400). Now all i would like to know is will the DDR800 work in my board that im currenty using 667(5300) in by running slower like to old DDR 400 did?? i hope you can all understand my waffling..all help very much appreciated.

 

[ckes101]

sorry every body i did not realize i had the caps lock on when doing the post description. Apologies..

 

[kmcferrin]

It shouldn't have a compatibility issue related to clock speed. You can always run the memory at a lower clock, and as a side benefit it runs cooler. If I were you though, I would want to test the memory in my system just to make sure that it works correctly.

A lot of times a given motherboard may only work with certain vendors' memory modules. I know it seems weird, but sometimes it happens. That's why I always recommend going with something that is listed in the motherboard's manual as being compatible.

One area that I have seen that appears ripe for problems is with memory voltages. The official DDR2 spec calls for 1.7-1.9v memory. However, many of the DDR2 modules that I have seen advertised (especially those with higher clocks speeds or higher latencies) require 2.0-2.2v in order to operate at the rated speeds. This is essentially factory overclocked memory. If your motherboard can't provide that much power, then you could run into problems. I have seen a number of Intel-based boards that specifically state that they do not support voltages in excess of the official DDR2 spec.

 

[ChillLead]

The primary difference btwn ddr & ddr2 is that ddr2 (2g memory) will "recognized" failed memory sectors and will not attempt to "write" to registers in the failed sectors whereas ddr is dumb and will continue attempting to "write" to registers in the failed (e.g., burned) chips on the module.

Also, mobo mfgrs rate there mobos for maximum ddr(2) frequencies. Overclocking will not exceed the frequency, but will force more voltage through a the module forcing the memory modules to run faster than they would at the "stock" rated voltage. Also, ddr and ddr2 are usually not compatable on consumer grade mobos; it's an either / or proposition: either ddr or ddr2, not both.

A better way to increase performance is to check the latency of the memory; here it's like a golf game: lower is better. Crucial has latencies in the 3 range.

 

[kmcferrin]

The primary difference btwn ddr & ddr2 is that ddr2 (2g memory) will "recognized" failed memory sectors and will not attempt to "write" to registers in the failed sectors whereas ddr is dumb and will continue attempting to "write" to registers in the failed (e.g., burned) chips on the module.

I'm not sure where you got that information, but it is definitely incorrect. The primary difference between DDR and DDR2 is that in DDR2 the bus that the memory module uses is running at twice the speed of the memory cells. Because of this it can transfer four words of data per memory cell cycle.

Also, mobo mfgrs rate there mobos for maximum ddr(2) frequencies.

I'm not even sure what you're trying to say here. Motherboard manufacturers rate their system with the highest support DDR2 rates, but that frequency varies between boards. Some are rated at 533 MHz, some at 667 MHz or 800 MHz. There might even be some rated at 1066 MHz or 1333 MHz, even though those clock speeds are into the DDR3 range. At any rate, it's all up to the board manufacturer and what they're willing to design for and support.

Overclocking will not exceed the frequency, but will force more voltage through a the module forcing the memory modules to run faster than they would at the "stock" rated voltage.

That is also incorrect. Overclocking by definition exceeds the stock specified frequency. With overclocking you are increasing the clock signal which controls the frequency, taking it OVER the spec clock speed. Hence the word "overclocking".

What you are talking about is overvolting, which is supplying more electical power to the circuit than it is specified for. And no, this will not force the modules to run any faster than they would at the stock rated voltage. It just means that they will consume more power and dissipate more heat, which could lead to system problems including premature failure of the overvolted components.

Often times overclockers will overvolt the component that they are trying to overclock. If an overclocked component is not running stably, sometimes overvolting makes the component run more stable at the overclocked speed. However, it also increases the amount of heat dissipated, and usually requires improved cooling to be successful without damaging your hardware.

 

[SteveLord]

Beware doing this with retail systems, like those from DELL. I put a PC3200 in a machine before, because I got it dirt cheap and thought it would just throttle down to PC2700 speeds.

The darn stick wouldnt even boot into the OS, so I ended up returning it and getting a PC2700 that I found other people had actually used and confirmed it working for that model.


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[kmcferrin]

Beware doing this with retail systems, like those from DELL. I put a PC3200 in a machine before, because I got it dirt cheap and thought it would just throttle down to PC2700 speeds.

The darn stick wouldnt even boot into the OS, so I ended up returning it and getting a PC2700 that I found other people had actually used and confirmed it working for that model.

As always, it pays to do your homework. Generally there is no issue running memory at a lower clock speed than it is rated for (ie, running PC3200 at PC2700 speeds).owever, you do have to take into account CAS latency settings. Also, when the memory module is probed by the mainboard for auto configuration, it may return values for clock speed or CAS latency that the mainboard does not support. In those cases you may have to either set those values manually in the CMOS setup (if possible) or use memory that more closely matches the mainboards specs.