Edgar1 Posted October 13, 2007 Share Posted October 13, 2007 Hi, the datasheet of the TWIN2X2048-6400C5DHX says the SPD is programmed at 5-5-5-18 and runs with 1.8 V. The datasheet of the TWIN2X2048-6400C4DHX states it runs with 4-4-4-12 at 2.1 V, and the SPD is programmed too with 5-5-5-18. However, it does not say at which voltage it runs with 5-5-5-18. In this thread it is asserted that the C4DHX does run at 1.8v, but this merely comes from a user, referencing the same data sheets but in which I personally cannot find proof of this claim. I don't want to overclock, I just need the missing piece of information. Please shed light on this question. TWIN2X2048-6400C4DHX - SPD Programmed @ 5-5-5-18 (1.8v) <-- please confirm this TWIN2X2048-6400C4DHX - "tested" @ 4-4-4-12 (2.1v) TWIN2X2048-6400C5DHX - SPD Programmed @ 5-5-5-18 (1.8v) Link to comment Share on other sites More sharing options...
DerekT Posted October 13, 2007 Share Posted October 13, 2007 Hi, the datasheet of the TWIN2X2048-6400C5DHX says the SPD is programmed at 5-5-5-18 and runs with 1.8 V. The datasheet of the TWIN2X2048-6400C4DHX states it runs with 4-4-4-12 at 2.1 V, and the SPD is programmed too with 5-5-5-18. However, it does not say at which voltage it runs with 5-5-5-18. That is at the JEDEC voltage standard of 1.8v. In this thread it is asserted that the C4DHX does run at 1.8v, but this merely comes from a user, referencing the same data sheets but in which I personally cannot find proof of this claim. I don't want to overclock, I just need the missing piece of information. Please shed light on this question. TWIN2X2048-6400C4DHX - SPD Programmed @ 5-5-5-18 (1.8v) <-- please confirm this TWIN2X2048-6400C4DHX - "tested" @ 4-4-4-12 (2.1v) TWIN2X2048-6400C5DHX - SPD Programmed @ 5-5-5-18 (1.8v) This is why it is programmed in the SPD settings. If it didn't work in the SPD settings and the motherboard demanded 1.8v, then it would not boot. Link to comment Share on other sites More sharing options...
Edgar1 Posted October 13, 2007 Author Share Posted October 13, 2007 That is at the JEDEC voltage standard of 1.8v. This is why it is programmed in the SPD settings. If it didn't work in the SPD settings and the motherboard demanded 1.8v, then it would not boot. Sloppy unclear answer and probably wrong. Yes, the JEDEC voltage for DDR2 SDRAM is 1.8v, but reading the JEDEC specification (4_01_02_10R14B.pdf) only the "Voltage Interface Level" is stored in the SPD, that is, for DDR2 it says some bit pattern which means "SSTL 1.8V". From my understanding _every_ DDR2 module intended for use in a standard desktop PC has this value in it, since DDR2 happens to have 1.8v specified back then. Point is, there is no way to put "it runs on 1.9v" (or something different) in the SPD (EPP is another matter), and therefore the user has to be aware of putting a RAM module in a motherboard which is able and willing to deliver more voltage than 1.8v. Take the XMS2 Pro for example, TWIN2X2048-6400C4PRO and TWIN2X2048-6400PRO. The latter is programmed for 5-5-5-12 (and "SSTL 1.8V") but needs 1.9v for normal operation. The former is intended to be used with 4-4-4-12 at 2.1v, but in "SPD-mode" it runs with 5-5-5-18 at 1.9v. The "base voltage" is the same. Now, Intel non-highend/non-gamer motherboards like the DP965LT, DP35DP and others only deliver 1.8v. Putting one of said RAM kits with 2 XMS2 Pro modules in it only works by chance, because it is in the tolerance of what the motherboard is able to deliver. Putting 4 modules in it does not work, the RAM modules overheat, the system lags and is unresponsive and therefore essentially unusable (besides something may break). For clarification here a similar table: TWIN2X2048-6400C4PRO - SPD Programmed @ 5-5-5-18 - needs 1.9v TWIN2X2048-6400C4PRO - "tested" @ 4-4-4-12 - needs 2.1v TWIN2X2048-6400PRO - SPD Programmed @ 5-5-5-12 - needs 1.9v So far so good. Now I _suppose_ the newer DHX modules behave in a similar way and the C4DHX in "SPD-mode" has the same "base voltage" like the C5DHX, which is the 1.8v which JEDEC originally specified for the DDR2 standard and which Intel only cares about. Another factor for assuming this is when we say that a series like the Pro series and the DHX series come from the same production line respectively. The C4 modules are then chosen when meeting some requirements but the base specifications for the chips of one specific production line are the same. So the older Pro generally run on 1.9v and the newer DHX generally run on 1.8v. To make a long story short: I'm politely requesting a confirmatory statement from someone who actually knows. Link to comment Share on other sites More sharing options...
DerekT Posted October 13, 2007 Share Posted October 13, 2007 From my understanding _every_ DDR2 module intended for use in a standard desktop PC has this value in it, since DDR2 happens to have 1.8v specified back then. And you say "I'm" unclear and probably wrong? :P Yes, I can see you need far more instruction. RamGuy can deal with you. :biggrin: Edit: He works weekdays and is off on the weekends. Look to a response on Monday. Link to comment Share on other sites More sharing options...
Edgar1 Posted October 13, 2007 Author Share Posted October 13, 2007 And you say "I'm" unclear and probably wrong? :P However, it does not say at which voltage it runs with 5-5-5-18. That is at the JEDEC voltage standard of 1.8v. Yeah, you're right, but it seems to me by chance, since you knew the DDR2 standard says 1.8v, you just stated that and if it holds true the DHX actually do abide by the standard. If I happened to ask the same question for the Pro modules I can imagine I would've got the same answer of 1.8v (it doesn't say there in the datasheet either). far more instruction. I'd merely be satisfied with an answer of "yes" or "no" to my question of essentially "Am I right?" :biggrin: He works weekdays and is off on the weekends. Look to a response on Monday. Thanks for the hint. Link to comment Share on other sites More sharing options...
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