View Full Version : Hardware question

05-06-2002, 05:45 PM
What determins the amount or RAM you can upgrade your computer with? Isn't it something about cache?

How many harddisks does a computer support? Do include external harddisks...

Just give me a geeky answer...I can handle it...

05-06-2002, 06:08 PM
the amount of RAM that can be supported is dependent strictly on the motherboard. As for harddisks, it can support as many as you can plug in (IDEs, USB externals, etc.)

05-06-2002, 06:12 PM
How are you supposed to know how many RAM your motherboard supports? Where do you check that?

I always thought that there was a limit to how much "space" your computer supports. Maybe it's a software question.

Squally Leonharty
05-06-2002, 06:32 PM
You have normal RAM, DRAM, SDRAM, DDRAM, and many more.

To keep this all easy, most motherboards support 256 MB RAM chipsets, like mine. My computer has 320 MB RAM with 256 MB and 64 MB chipsets. There's another slot for another 256 MB. :p

Anyway, if your computer is a Compaq Presario, you have most likely SDRAM, which can be easily bought, sine it's the most common RAM available. You should be able to find the details here: http://www.orderingmemory.com/compaqconsumer/
It also has RAM details for other computers, such as Apple and Intel. :D

05-06-2002, 06:39 PM
So RAM upgrading has nothing to do with the "cache memory"-thingy?

Squally Leonharty
05-06-2002, 06:57 PM
What do you mean with that? RAM doesn't cache memory, so far I know. I'm not too sure, though. Just explain what you mean with it, and I, or someone else, will be able to explain it. :)

05-06-2002, 08:35 PM
That someone else normally ending up being me, eh, Squally? :p

The cache memory he's talking about is special RAM biult onto the actual processor to help speed memory access up - it's rarely more than 512k at the moment because it's so expensive, and being built onto the processor chip die, upgrading that means replacing the processor :D

As for he main RAM, if your PC is fairly new, ignore the stuff about SDRAM/DDRRAM etc. (though you'll need to know when actually buying which one's your mothr board supports) - easy way to work out how much RAM your motherboard will probably support amx is count the number of slots there are for RAM (including used ones), and multiply by 512 MB for each slot. For example my motherbaord has 3 slots for RAM (1 used), so I could have up to 1.5 GB RAM :)

As for HDs, there's not really a limit as such.

For internal drives, it's only the amount of space inside the case thats limiting it, though you'll need to remember to leave space for ventilation and/or add extra fans and such, you don't want the things overheating. Normal PC configurations will only let you have 4 HDs + CD/DVD drives in total, if you want to go above that you'll need extra controller cards, each one requiring a spare slot on the motherboard to plug into. You'll also need to make sure you have adequate power supply inside the PC if you're going to have at least 3 good performance ones too.

For external drives, then as many as you can plug into the machine via SCSI cards (each SCSI card needs a slot too on the motherboard). You'll probably need a seperate power socket/source for each one though.

And I think some older OSs liek WinME and Win98 won't recognise more than 24 drives, due to the lettering style it uses to access them :p WinXP and Unix-style OSs should have no problem with that many disks though.

I'm sure there's more to say but I can't remember much else off the top of my head for now :D

05-06-2002, 09:42 PM
Okay...I know that RAM modules come in two form factors:

Now DIMM has 168 and a SIMM has 72 pin..or was it contacts? ...erh..Should have payed more attention in school...
...should one pay attention to those differences?

I've heard that RDRAM only works on Rambus which is in the P4. Why is that? Is it even true? Does AMD not support it?

A further question if I may....heh...

What's the difference between CAS1, CAS2, & CAS3? For that matter, between PC100 and PC133 DIMM too?
I know that CAS is the latency of the ram...right?

05-06-2002, 09:53 PM
Yes, 168 pin and 72 pin memory modues are different, you need to know which ones your motherboard takes :) More likely 168 for newer motherboards.

Not sure about RDRAM only working with P4, but I do know it only works in Pentium chipsets, so it wouldn't work with an Athlon processor.

PC100 and PC133 tell you the max speed of the bus supported by that RAM at it will stay stable at - PC100 for a 100MHz bus, PC133 for a 133MHz (faster) bus. Again, it's best to know what your motherboard bus speed is - there's no point getting PC133 RAM for a 100 MHz bus, since it'll only operate at 100 MHz then, unless you plan to upgrade that motherboard in the future or something.

CAS or the latency of the RAM kind of measures the speed at which data can be read/written to (not quite though, but I don't fully understand it myself), in ms - so the smaller the better. I think my RAM is CAS3 but I've explicitly told the BIOS treat it as CAS2 - it'll be my fauilt if I get memory read.write errors, but I've yet to have any and had it set at that for months now :p

05-08-2002, 11:43 AM

How do I change the speed to 2 Gb/s in the drive? I have a 2 Gb/s FC initiator card and want to interface with Cheetah X15 drive.

And, please let me know what the difference between LVD and LVD/SE is. I don't have a clue.

05-08-2002, 01:15 PM
How do you mean change the speed of the drive? You mean as in what mode is used to access it e.g PIO4 or UDMA Mode 2 etc.?

And I have no idea what LVD is :p Laser Disc, perhaps?

05-08-2002, 01:49 PM
The speed is controlled by pin 39 of the interface connector. If this pin is open, or held high when the drive is powered up, the drive will default to 1Gbs. If the pin is held low at powerup, the drive will run at 2Gbs. There should be something that I can control/select the thingy with, but I don't know what or how to.

Low Voltage Differential (LVD), Ultra-2 and Ultra-3 capable drives also support Single Ended (SE) mode. This feature is called "multimode".
Differential is a method of carrying the signals over the cable. Each signal is carried on two wires, with each of the two wires carrying the signal 180 degrees out of phase (meaning, when the signal on one wire goes high, the signal on the other wire goes low). This is decoded at the receiver end by comparing the two together to see what the relative difference is in the two. This is highly resistant to outside interference, as any interference would affect the amplitude of the signal, but not the phase relationship.
I don't really know what SE is:p but I don't think it's the same as LVD.

05-08-2002, 07:03 PM
Sorry, can't help you any more, I'm not that much of a hardware enthusiast :p

05-08-2002, 08:57 PM
Don't make me go ask in a geeky forum...They'll butcher me for asking such a "simpel" question.... Anyway, I'll ask again in this thread if I have further questions...Or I'll make a new thread concerning software.;)

05-08-2002, 09:45 PM
If you're talking about hds and their cable, all I know is that the cable is different when using high speed dma (udma66 to udma133), but I suppose it doesn't help you much. Check your mb manual or bios or controller manual, you may find how to enable 2 Mb. *is not hardware savvy*

Oh, a correction about max ram. Today's mbs can handle up to 3 x 1Gb of DDR. Mine does at least :p

05-09-2002, 10:56 AM
Originally posted by Master Vivi
Oh, a correction about max ram. Today's mbs can handle up to 3 x 1Gb of DDR. Mine does at least :p