ADE

OK, I read on eBay that low density RAM is compatible with all computers and high density RAM isn't. I know that already, but I didn't know that high density RAM is SLOWER than low density. Is this true????

PC eye

Higher density has more to do with capacity then speed depending on type. The first cd-rs were only 60min. in length for audio tracks. The next generation was the slightly higher 74min. cd-rs soon to be replaced by the 80min. disks commonly used.

A double density floppy was 2.88mb instead of 1.44mb. When selecting memory you have to go by the type or types supported. Again some boards won't support a 1gb dimm which is a higher density then a 512mb although they are the same size. Memory frequency speed and CAS latency controls which memory is faster. DDR400 at 400mhz is faster then DDR333 at 333mhz. DDR400 with a lower set of timings like 2-2-5-2 is faster then the typical 3-3-3-8.

ADE

So weather its high of low it will be the same speed?

SirKenin

haha.

Oh man, don't listen to PC Eye.. Whatever you do.

Low density/High density refers to the number of chips on the stick. Low density is 16 chip (usually reserved for older boards), high density is 8 chip.

I'm not aware of a speed difference between the two.

Motoxrdude

Is it like single sided ram and doubled sided ram?

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Cromewell

No, high density RAM means each chip can be larger so you need less to make an X MB stick of RAM.

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PC eye

It's school time kiddies! How about some basic facts!

Types of RAM

RAM comes in different types and flavors to suit different needs and budgets. There are many specialized types of RAM, but some of the more common types are:

• SRAM. Static Random Access Memory is very fast and very expensive. It is primarily used for memory caching (such as on processor chips). Architecturally, it has multiple transistors for each memory cell. It does not need to be refreshed.
• DRAM. Dynamic Random Access Memory is slower than SRAM and needs to be refreshed many times every second. Each memory cell consists of a capacitor and a transistor. DRAM is much less expensive than SRAM.
• SDRAM. Synchronous Dynamic Random Access Memory is a special type of DRAM that is synchronized to the system clock. Each chip contains internal registers that accept requests from the CPU, thus freeing the cpu to do other things while the data is assembled. Since SDRAM is synchronized to the CPU, it "knows" when the next cycle is coming, and has the data ready when the CPU requests it. This increases efficiency by reducing CPU wait states. SDRAM is available at speeds as high as 133 MHz.
• DDR-SDRAM. Double-Data Rate SDRAM works the same way as does ordinary SDRAM, except it works twice as quickly by synchronizing to both the rising and falling of the clock pulse (which makes it twice as fast as ordinary SDRAM). DDR-SDRAM can also be installed in dual-channels if the motherboard supports this arrangement. There is no difference in the actual RAM modules used for dual-channel DDR, but the two sticks of RAM in each channel must be a matched pair (same size and speed).
• RDRAM. Rambus Dynamic Random Access Memory is a very fast type of RAM in which the chips work in parallel to produce very fast speeds. However, because it is proprietary and very expensive, RDRAM has been slow in catching on.

Choosing RAM (See also: Installing RAM)

What type of RAM Should I Choose?

You must decide what type of RAM your homebuilt computer will use before you buy a motherboard. This is because most motherboards are able to use only one type of RAM.
Ordinary SDRAM is rapidly becoming obsolete. So if you are building a new computer, chances are you will be deciding between DDR-SDRAM or RAMBUS.
Unless you are building a computer that will require truly massive speed (even beyond that required by all but the most high-pressure gaming applications), we suggest that you use DDR-SDRAM. It's fast, stable, and relatively cheap.
DDR-SDRAM can also be installed in dual-channel configuration, if your motherboard supports it. When using dual-channel DDR, pairs of identical RAM modules work in tandem to greatly improve performance. Both the size and the speed (and preferably, the manufacturer, in our experience) of each RAM module in a dual-channel pair must be identical.
If you want the absolutely fastest RAM available, then look into RAMBUS. But be prepared to spend several hundred dollars on RAM alone. Like dual-channel DDR, RAMBUS modules must be installed in identical pairs.
How Much RAM do I Need?

Dollar for dollar, nothing will liven up your homebuilt computer more than endowing it with a respectable amount of RAM. In addition, because RAM is so central to your computer's functioning, always choose RAM made by a reputable manufacturer like Crucial.
Every operating system has "minimum system requirements" for processor speed and RAM; but in our experience, the minimum requirements tend to be grossly inadequate if you actually want the computer to do anything useful. Instead, we suggest the following RAM amounts for optimal performance of desktop PC's running the following popular operating systems:

Windows 98/Me: 256 - 512 MB
Windows 2000/XP: 512 - 1024 MB
Linux (kernel 2.2 with x-server): 256 - 512 MB
Linux (kernel 2.4 or 2.6 with x-server): 512 - 1024 MB
Linspire (formerly Lindows): 512 - 1024 MB

If you use your computer for graphics manipulation, video editing, TV or DVD viewing, gaming, CAD/CAM applications, or complex mathematics, then you should lean toward the higher numbers. If you mainly use it for email, web surfing, and office apps, than the lower numbers should be sufficient.
There does come a point when you are not likely to see any noticeable improvement by adding more RAM. Going very much above the higher figures in the table above is not likely to improve your computer's performance in any noticeable way. And of course, you cannot install more RAM than your motherboard can support; so make sure you know this figure before buying up every last stick of RAM in the store!
RAM Speed

The speed of RAM you will need depends mainly on the motherboard. You generally should choose the highest speed of RAM that the motherboard supports. Make sure that you check the motherboard documentation to find this out. Just because a stick of RAM fits in a motherboard doesn't mean it will work. Sometimes, inserting the wrong RAM and powering up the mobo can damage the board, the RAM, or both.
Even if your motherboard can support different RAM speeds, using slower RAM than the fastest that the mobo supports means you won't get the maximum performance that the board is capable of delivering.
As the speed capabilities of RAM of a given type improve, newer, faster RAM is usually backward-compatible to slower speeds. This is accomplished through the use of a serial presence detection circuit built into the RAM module. So for example, most PC-2700 (333 MHz) DDR-SDRAM sticks are backward-compatible to PC-2100 (266 MHz). So if your board is built for PC-2100, but you can get PC-2700 for the same price, you may as well go for the faster RAM. You never know: You may want to use it in your next project. (Just make sure that the RAM you buy is backward-compatible to the speed you need now!)
The one thing you generally should avoid, however, is mixing RAM speeds in the same computer. In theory, if you mix RAM speeds, all of the modules should clock to the lowest speed; but in practice, mixing speeds (and sometimes even brands) in the same PC can cause system instability. (And of course, RAMBUS and dual-channel DDR must use matched pairs of identical modules.) http://www.kitchentablecomputers.com/ram1.htm

Arm_Pit

School time like your first post? =P

Cromewell

Your copy-paste has schooled me. I am learned now

What does that have to do with what high/low density RAM

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SirKenin

What does anything he ever posts have to do with the thread??

http://www.4allmemory.com/index.cfm?...ils&faq_id=102