Slashdot Mirror
PCI RAM Extender Cards?
stevejsmith asks: "I'm going to buy a Dell computer which supports DDR RAM, however it only comes with two DIMM slots. I have lying around two 128MB sticks of RAM, and want to use them. I know RAM is cheap, but I want some way to put more than two DIMMS in this system. Short of getting a new motherboard, is there any way I can add more RAM? On Slashdot I remember seeing a PCI card that help RAM for a RAM drive, but is there such thing as a PCI card that just held regular RAM for system usage? If not a PCI card, any other suggestions?"
Putting ram on a PCI card is a bad idea in this day and age, peak PC2700 memory bandwidth is 2.7GB/s, peak 32/33 PCI bandwidth is 132MB... that presents something of a bottleneck :)
Just buy a computer with a sensible number of dimm slots to begin with.
Well, sort of.
It's an IBM MCA expansion board which supports 4 EDO-RAM.
#include "coucou.h"
Of all the things that a motherboard (or more specifically the collection of microchips known as the chipset) connects together the connection between the memory and the processor is the fastest the most important to performance. No other link, except between the processor and the motherboard even comes close in importance. Also, another issue that comes up is what is known as latency. Latency is the delay the system experiences when it requests memory access. It's not just how much data you can transfer, but how quickly you can have it after you ask.
For all those reasons it almost always makes sense, especially at today's prices, to have all the same memory modules in your system and the fastest memory your system can support. Even if you are able to recycle memory I would avoid doing so unless stability is an issue as many technical issues arise when DIMMS are mixed and matched.
The performance hit from this will negate any benefit you will get - you might as well just leave out the ram as it will be slowed down to PCI speed. As you said, RAM is cheap, so sell what you've got and buy one or two 512MB sticks.
Free Java games for your phone: Tontie, Sokoban
People have already mentioned its a bad idea. You may take them at their word, it is.
But that said, why even buy a system if it limits you before you have even opened the box? Ram is so cheap nowdays you have to be really stingy to not meet your base requirements, even if that includes a ton of Photoshop work, or most any other ram-intensive app. (Server stuff not withstanding.)
If possible, buy your Dell with minimum RAM posible, and buy 3rd party ram new to replace it, the largest size you can buy on a DIMM. That will give you 2x the maximum. If that isnt enough though, DONT BUY THAT SYSTEM! As for using the old ram, that will only slow your system down anyway. Deal with obsolescence and either reuse it in another system, sell it for a token sum, or give it away to someone who can use it. I tend to pass old hardware I have no need of anymore to friends or family.
Anyone who considers arithmetical methods of producing random numbers is, of course, in a state of sin.-John von Neumann
Throw out the 2 128s and buy 2 larger DIMMs. I can send you a few dollars if you need help.
- A.P.
"Remember when the U.S. had a drug problem, and then we declared a War On Drugs, and now you can't buy drugs anymore?"
Posted by Cliff on Sat November 16, 03:13 PM
from the I-have-no-idea-what-bus-bandwidth-means dept
Look up the specs on your chipset, as it may support more than 2 sticks of memeore, but the mobo was manufactured with only 2 slots
as for getting an extra stick in, you would have to hardwire a stick or connector to the chip
"I'm going to buy a Dell computer which supports DDR RAM, however it only comes with two DIMM slots.
Well there is your problem right there. Buy a machine with a different motherboard. If people keep buying machines with only 2 slots then companies have no incentive to supply boards with more slots. Personally I wouldnt buy a pre-made machine - ever. I prefer to have control over every component. (Obviously I'm not talking about the Mac here).
You dont want your main memory over PCI, plus I dont know if any mainstream OS supports this. On the other hand, if you could put a gig of sdram on a pci card and have it look like a 1GB hard drive.
...
Then you mount swap on it. This makes swapping very very fast. And increases performce once you start swapping.
Now all you need is a card that can do it
Are you paranoid if you know that they just want to know everything you say and do?
You are really looking for one of these: http://www.futureplus.com/products/ddr/1012_drawin g.html
They used to make these for 30-pin and 72-pin, but seemed to stop when 168 and 184 pin dimms rolled around. I only did about 5 minutes of searching on google, but you might be able to find someplace actually selling that.
OK. This used to be a valid concern when people had mountains of 1 or 2 megabyte sticks that were still worth about $400 each, but seriously, just buy new RAM. Nobody makes "simm stacker" type devices for large DIMM's. Those 128MB DIMMS you have are what, like $15 new? How much do you think any specialty product like this is going to cost.. Probably more than the $30 of ram you want to stick in it.
It doesn't really make a lot of sense when you can just buy a couple of 256 or 512mb sticks for somwhere between 100-200 bucks.-- Or buy a computer that doesnt suck. (The dells with only two ram slots are pretty budget)
i remember seeing (several years ago ) what would have been the equivalent of a power strip for ram. it was a ram-sized board that fit in a 72-pin simm slot, which itself could hold up to 4 simms. i'm not sure if they still make them, or if they do, i'm not sure if they make them for any of the newer ram types.
Somewhere on this page I have hidden my signature.
There's your answer right there: dude, don't get a dell. Get something that supports more slots, and get what you want.
Bus RAM made sense on my 286 running windows 3.0. Real-mode paging was a real step up from the 1M memory limit.
Today it doesn't make any sense.
OTOH, the ram drive you mentioned might make sense (except that it is pretty expensive) if you used it for a swap partition.
I think that a better overall plan would be:
1. Don't buy a RAMBUS based system.
2. Buy one that supports an unreasonable amount of RAM, with only one slot populated with the largest module it supports. In a few years it won't seem like so much.
3. Reconsider buying a Dell. If you know how many DIMM sockets it has you aren't the target customer.
-Peter
If this is a cheapie P3/Celeron Dell, based on an 815 chipset, that would explain the two slots. 815 chipsets are limited to 512 meg of ram, no matter what you do.
2 x 256 fills that up nicely, there's no point in having 3 slots, what are you going to do, 2 x 128 + 1 x 256? Just doesn't make sense.
1. Get a different motherboard. OR
2. Buy new RAM and sell the old on Ebay.
...to put system RAM on the PCI bus. RAM needs to talk directly to the L2 cache, and in this day and age that means the processor. DDR RAM is so cheap you really shouldn't bother. If you want to do something useful with your old memory, go to a local school and upgrade one of their PCs with it!
The board you mention was probably the HyperDrive, a PCI based pseudo-hard disk drive that uses an external power supply and SDRAM as the media rather than a physical spinning magnetically coated disk. They require quite specific amounts of memory and you pay more the more they take, even if you get them without the DIMMs.
Resistance is futile. Reactance buggers it up.
(Yes, I am going to keep posting this until you either update it or remove it as your homepage.)
;)
Moderators: Don't waste your mod points on modding this post down, please. Mod up some of the other stuff on this topic (like the parent, which I would consider "Insightful"...
A PCI ram expansion will have abysmal performance because the bandwidth of the PCI bus is limited to 133mb/sec, which is only about twice as fast as a good hard drive swap file and 1/8 the speed of PC133 SDRAM, or 1/20 the speed of PC2700 DDR.
A 512mb PC133 stick is $50, and a 256mb PC2700 stick is $80. PC2100 is about $65 for 256mb. That's cheaper than getting a new mobo. Just throw out one of your 128mb dimms and replace it with a bigger one.
Repeal the DMCA!
So why no AGP based solutions? There should be far more than enough speed on a good 4x AGP slot to handle this. Of course, it would either entail some kind of video-card pass-through (messy and probably torally impossible) or simply your choice to have a server machine with 4 Gigs of cheap memory and a Trident 8900 videocard.
I think it's about time for this -- 128 MB and 256 MB sticks are dirt cheap... go up past 512 MB and you're creeping towards the double the price per MB mark.
If you could be told what you can see or read, then it follows that you could be told what to say or think - BoC
Not what is intended here though.
Consider something along the lines of a Squid cache built using inexpensive harware, that boots from flash. Because it's inexpensive, the chipset only supports, say, 512MB RAM. But you want an 8GB cache (hypotheticals courtesy of Swelltech for 1 T-1s worth of bandwidth. So we're talking solid state here.
Someone's going to go off half cocked here and say I'm talking out both sides of my mouth, inexpensive but blah blah blah. We'll I *produce* similar devices now for clients (I don't necessarily CHARGE inexpensive because of the huge benefit they receive, what it would cost them for something similar) only I'm currently stuck using hard drives. So what if this RAM based psuedo-drive is PCI bus bound. I don't need it to persistently store data between reboots.
>I can build them to my precise specs cheaper than I could buy them pre-made.
No, you can -usually- build them cheaper than you can get them pre-built. Of course some times you get lucky and catch Dell blowing out old stock.
I bought a Dell Poweredge 500SC server (1.2GHz with two 80G IDE drives, CD-ROM, keyboard/mouse, Intel Pro100b NIC, etc... no monitor) for $315 (plus tax) delivered. That's less than $2 a gig for the entire server for a gigahertz+ class machine. If it breaks they send someone to my house to fix it (as if!)
For the record, Dell memory is hideously expensive. I upgraded the server to 1G of ECC registered for another $100 (yea Fry's!) It has three more slots for RAM in case I am feeling frisky.
Glonoinha the MebiByte Slayer
you mean something like this
"I assumed blithely that there were no elves out there in the darkness"
Hmmm, you have a point there. There are a fair few cheap "server" motherboards in use in small companies with AGP slots free... IIRC AGP has much higher b/w, with less-latency, than vanilla PCI. Anyone with throughput figures?
However, device manager ("view by connection") in my Win2K system shows the AGP card hangs off the PCI bus via a PCI-to-PCI link. Does this mean that AGP runs off a higher-speed PCI bus?