The Secrets of PC Memory: Part 2 - bit-tech.net Forums

Tim S · 17th Dec 2007, 08:11

http://www.bit-tech.net/hardware/200...emory_part_2/1

In the second part of this series on PC memory technology, Ryan investigates the secrets behind mobile DDR and self-refreshing technologies, power down modes and chip packaging technologies.

DarkLord7854 · 17th Dec 2007, 08:19

Note to self: Don't attempt to decipher at 3am

Tyinsar · 17th Dec 2007, 09:04

Quote:

Originally Posted by DarkLord7854

Note to self: Don't attempt to decipher at 3am

LOL, it's 2am here but I'm thinking the same thing. I look forward to reading this tomorrow. Thanks Bit-tech & Ryan.

Woodstock · 17th Dec 2007, 09:13

its only 10pm here and im thinking the same thing but ive been up since 4am (why cant cows milk them selves)

metarinka · 17th Dec 2007, 09:28

interesting, does stacking or other physical methods of increasing memory density increase the need for proper cooling?
ugh it's 4:37 here and I got an exam at 8 >_< this study break contained more information than my actual studying

Almightyrastus · 17th Dec 2007, 13:36

I should think that the stacking of chips would make cooling things a little trickier although if something along the lines of the dominator cooling system were used this could be helped. By this I mean that as the Dominator uses the pcb to cool the underside of the chips, the stacked chips could be held together by some kind of thermal tape that would come out from between them and bond onto the heatsink. Just a thought.

Redbeaver · 17th Dec 2007, 14:02

dont try to decipher this 8.30AM Monday morning. read: MONDAY. bad idea.

but overall, amazing article. very informative. some stuff reminded me of college, some stuff ive never ever heard before, some stuff is just simply inspiring.

bravo.

ryanjleng · 17th Dec 2007, 14:41

FYI, I was probably drunk and tripping high on DMT when writing these stuff

m (*.*) m

A lot of the chip or module stacking are temporary solutions to a demand for larger capacity. These are usually used for advance server/storage systems. Performance is almost always secondary to signal reliability in these cases.

A lot of the stacking methods can produce signal irregularities at super high speed, so overclocking is a bad idea. That is why we don't see them as much in desktop market. The only stacking solution that works better is with the die, which we do see a lot in the desktop market.

Special PCB cooling solution (ie. Corsair Dominator series) is used to drain the heat downward in order to have a more even thermal expansion and contraction between Chip and PCB.

Micron D9 series on a cheaper standard PCB can often overclock as well with super expensive PCB, and we do find D9s in value/budget ram. Only problem is when the VDIMM is too high and the hot chip expand excessively, it cracks the connectors at the bottom.

ryanjleng · 17th Dec 2007, 22:23

some after thoughts...

About Moore's law
--------------------------
Moore's Law is often referenced to the CPU, but the PC is a compilation of systems with the processor as the center. Hence, it is a requirement for all connected sub-systems to perform in-step and up to speed with the processor.

In the lab, we see many system instabilities attributed to the memory partly because of shrinking safety margins. On very high speeds like 1600MHz ++, if the motherboard and memory module is not engineered properly, the rig cannot run Dual-Channel in a stable manner.

These kinds of instability cannot be easily detected by Memtest86 and variants. Use Prime96's torture tests with emphasis on RAM.

On Chip fabrication
--------------------------
Having lower power is technically a requirement with miniturization. With each generation of IC fabrication, the insulators are getting thinner between conducting elements. With a higher voltage, a thin insulator has problem preventing electrical current jumping across. A large margin of safety is dictated in the JEDEC standard in this respect, but not all DIMM makers follow them.

Overclocking with VDIMM tends to do many nasty things to the trace circuitries, specifically destroying the insulation. It looks like badly cooked cheese.

Interestingly, electro static literally create bomb craters on the conducting circuits.

Ghys · 17th Dec 2007, 22:31

It's the 3rd time in two days that I partially see the title of this thread or article and think I read "The secret of monkey island" only to go back and see it has nothing at all to do with it

sandys · 18th Dec 2007, 00:06

Blimey Microns cell is small, a few years back I did an 8T bit cell layout, quite tough as these layouts don't follow the rules and require a lot of process knowledge to estimate OPC improvements, my cell was a lot bigger than this and took ages due to the effort involved in shaving every last nm off, funny when you think how simple it was, essentially a couple of inverters and some pulldowns you'd think it'd take 5 mins.

Phil Rhodes · 18th Dec 2007, 16:30

What I always find alarming is that we refresh DRAM in modern PCs at some ludicrous number of cycles a second, but if you actually try it on an electronics test bench, quite a lot of it will maintain its contents for... well, I've seen over a minute myself with nothing more than Vcc connected.

ryanjleng · 19th Dec 2007, 10:10

Quote:

Originally Posted by Phil Rhodes

What I always find alarming is that we refresh DRAM in modern PCs at some ludicrous number of cycles a second, but if you actually try it on an electronics test bench, quite a lot of it will maintain its contents for... well, I've seen over a minute myself with nothing more than Vcc connected.

i think temperature may be a factor here. the warmer it gets, the faster the leakage.

Moreover, JEDEC always insisted on extra safety margins and leave nothing to chance.

17th Dec 2007, 08:11	#1
Tim S Pewlius Caesar bit-tech Staff Join Date: Nov 2001 Location: Ascot, Berks Posts: 18,021	The Secrets of PC Memory: Part 2 http://www.bit-tech.net/hardware/200...emory_part_2/1 In the second part of this series on PC memory technology, Ryan investigates the secrets behind mobile DDR and self-refreshing technologies, power down modes and chip packaging technologies. __________________ Tim on Twitter \| Tim's Blog \| Tim's Flickr The bit-tech Blog \| bit-tech on Twitter \| Join the bit-tech & Custom PC folding team (#35947)

17th Dec 2007, 08:19	#2
DarkLord7854 Web Developer Join Date: Jun 2005 Location: West Palm Beach, Florida Posts: 3,832	Note to self: Don't attempt to decipher at 3am __________________ Current Computer: eVGA 780i Motherboard \| Q6600 Core2Quad \| eVGA GTX260 896Mbs 216-core \| 2x Seagate 500Gbs \| 8Gbs OCZ Platinum DDR2 800 \| Creative XtremeGamer X-Fi \| Thermaltake Armor Case Custom WordPress, ZenCart, Joomla, vBulletin, etc installs and skinning, PM/E-Mail for a quote

17th Dec 2007, 09:13	#4
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17th Dec 2007, 09:28	#5
metarinka I am a Dremel Join Date: Feb 2003 Location: Michigan Posts: 1,621	interesting, does stacking or other physical methods of increasing memory density increase the need for proper cooling? ugh it's 4:37 here and I got an exam at 8 >_< this study break contained more information than my actual studying __________________ project: Orbitoid project: Orbitoid discussion Project: Angry-9 the WWII radio

17th Dec 2007, 13:36	#6
Almightyrastus Heathen Join Date: Mar 2002 Location: Nottingham, England Posts: 442	I should think that the stacking of chips would make cooling things a little trickier although if something along the lines of the dominator cooling system were used this could be helped. By this I mean that as the Dominator uses the pcb to cool the underside of the chips, the stacked chips could be held together by some kind of thermal tape that would come out from between them and bond onto the heatsink. Just a thought. __________________ Lo there do I see my Father. Lo there do I see my Mother, and my Sisters and my Brothers. Lo there do I see the line of my people, back to the beginning. Lo they do call to me. They bid me take my place among them, in the halls of Valhalla where the brave may live forever.

17th Dec 2007, 14:02	#7
Redbeaver Hypermodder Join Date: Feb 2006 Location: Ontario, CANADA Posts: 718	dont try to decipher this 8.30AM Monday morning. read: MONDAY. bad idea. but overall, amazing article. very informative. some stuff reminded me of college, some stuff ive never ever heard before, some stuff is just simply inspiring. bravo. __________________ Monita DFI NF4 Expert - X2 3800+ 2.925Ghz - 2x1Gb OCZ Gold XTC DDR500 - 2x eVGA 7900GT SLI - 2x80Gb Seagate 7200.9 [RAID-0 4k] - Enermax Liberty 500 - Vista Ultimate x86 - Silverstone Kublai [Modded] Keisha DFI BloodIron P35 - Q6600 3.6Ghz - 4x1Gb OCZ Gold XTC2 DDR2-800 - eVGA 8800GTS 640MB - 2x80Gb Seagate 7200.9 [RAID-0 4k] - OCZ GameXstream 700 - Vista Ultimate x86 - Silverstone TJ-06 [Modded] www.pecelayam.com

17th Dec 2007, 14:41	#8
ryanjleng ... Join Date: Nov 2007 Posts: 323	FYI, I was probably drunk and tripping high on DMT when writing these stuff m (.) m A lot of the chip or module stacking are temporary solutions to a demand for larger capacity. These are usually used for advance server/storage systems. Performance is almost always secondary to signal reliability in these cases. A lot of the stacking methods can produce signal irregularities at super high speed, so overclocking is a bad idea. That is why we don't see them as much in desktop market. The only stacking solution that works better is with the die, which we do see a lot in the desktop market. Special PCB cooling solution (ie. Corsair Dominator series) is used to drain the heat downward in order to have a more even thermal expansion and contraction between Chip and PCB. Micron D9 series on a cheaper standard PCB can often overclock as well with super expensive PCB, and we do find D9s in value/budget ram. Only problem is when the VDIMM is too high and the hot chip expand excessively, it cracks the connectors at the bottom. Last edited by ryanjleng; 17th Dec 2007 at 14:58.

17th Dec 2007, 22:23	#9
ryanjleng ... Join Date: Nov 2007 Posts: 323	some after thoughts... About Moore's law -------------------------- Moore's Law is often referenced to the CPU, but the PC is a compilation of systems with the processor as the center. Hence, it is a requirement for all connected sub-systems to perform in-step and up to speed with the processor. In the lab, we see many system instabilities attributed to the memory partly because of shrinking safety margins. On very high speeds like 1600MHz ++, if the motherboard and memory module is not engineered properly, the rig cannot run Dual-Channel in a stable manner. These kinds of instability cannot be easily detected by Memtest86 and variants. Use Prime96's torture tests with emphasis on RAM. On Chip fabrication -------------------------- Having lower power is technically a requirement with miniturization. With each generation of IC fabrication, the insulators are getting thinner between conducting elements. With a higher voltage, a thin insulator has problem preventing electrical current jumping across. A large margin of safety is dictated in the JEDEC standard in this respect, but not all DIMM makers follow them. Overclocking with VDIMM tends to do many nasty things to the trace circuitries, specifically destroying the insulation. It looks like badly cooked cheese. Interestingly, electro static literally create bomb craters on the conducting circuits.

17th Dec 2007, 22:31	#10
Ghys DUHHHH Join Date: Jan 2002 Location: Montreal, Canada Posts: 2,585	It's the 3rd time in two days that I partially see the title of this thread or article and think I read "The secret of monkey island" only to go back and see it has nothing at all to do with it __________________ Phenom X3 720 Black Edition @ 3.4Ghz - Asus M3N72-D SLI - 4GB PC6400 - MSI GTX260 216 - RAID0 37gb Raptors - 2x 500GB - Corsair TX850 - Samsung 2233RZ 120hz cheesecake - Windows 7 Ultimate 64Bits Kids ! The Samsung 2233RZ is the solution to all your problems in life ! That is, of course, if your biggest concern is not sucking at FPS games

18th Dec 2007, 00:06	#11
sandys Hypermodder Join Date: Mar 2006 Location: Bristol, UK Posts: 915	Blimey Microns cell is small, a few years back I did an 8T bit cell layout, quite tough as these layouts don't follow the rules and require a lot of process knowledge to estimate OPC improvements, my cell was a lot bigger than this and took ages due to the effort involved in shaving every last nm off, funny when you think how simple it was, essentially a couple of inverters and some pulldowns you'd think it'd take 5 mins. __________________ Into Gaming and around Bristol, UK, Click Here

18th Dec 2007, 16:30	#12
Phil Rhodes Supermodder Join Date: Jul 2006 Posts: 577	What I always find alarming is that we refresh DRAM in modern PCs at some ludicrous number of cycles a second, but if you actually try it on an electronics test bench, quite a lot of it will maintain its contents for... well, I've seen over a minute myself with nothing more than Vcc connected.