Faster Computer? Don't buy a new one - Just Add RAM

A long-time customer sent me a note yesterday about his problems with his assistant's computer.

It all started with his suggestion that a faster computer might be a good thing - but the assistant didn't want the hassles of moving everything over from Windows XP to Vista. OK - so my customer phoned up his favourite vendor - an multi-national tier-1 distributor and asked for a machine with the "Upgrade" option of XP installation instead of Vista (and commented to me how this really was a complete oxymoron - asking and paying for an "upgrade" to an older operating system)

Time went by and the system didn't arrive. Phone calls and more time, and he finally cancelled the order.

At this point he decided to heed my advice that I've given freely for years now - put in as much RAM as possible/practical to get the most out of your hardware and operating system. In this case the old computer was from another Tier-1 supplier and should not have been a slouch - fast CPU and not bad disk, etc. - but it only had 2x256 DIMMS in it for a total of 512 Megs of RAM. This on a machine with a CPU in the 2+ GigaHertz range.

Now my rule of thumb for years has been "1 Meg of RAM for each MegaHertz of CPU speed" - which in this case meant something around 2+ Gigs of RAM. The machine has 4 RAM slots and the specs say it will take 512Meg DIMMS in each slot for a total of 2 Gigs. My friend went down to the local computer shop and purchased 2-512Meg DIMMS - quoting the machine model number and all.

Well, it turned out that the sales person had given him the wrong RAM - almost fit but was not really even close - was 184 pin (old style) when the machine really required 240 pin DDR2 style.

His comment in his e-mail to me was "I've never forgotten words of wisdom you gave me 20 years or more ago... and that is that people who sell computers don't make their living by using them... the comment related mostly to advice about software for business functions... but it's also true of hardware... they know the spiel, not necessarily the technology."

The upshot is that, now that the new RAM is in place (and he has replaced the older CD-ROM with a new DVD-burner)  the machine is performing much better - and at minimal cost.

Read on for the rational behind putting more RAM in an older machine

RAM today is CHEAP!!!

In fact it is so cheap that it makes almost no sense to not fill whatever slots you have with as much as the machine will take, either now after you have purchased it, or if/when you purchase a new machine, however there is a point at which particular CPU/operating system mixes don't get any benefit from additional RAM.

For old Windows 95/98/ME the point is 256 Megs

For newer systems including NT, XP, 2000, 2003 the limit seems to be 2 Gigabytes but in some cases may be 3 Gigabytes on 32 bit hardware (traditional Pentium-style CPUs) Note that on most motherboards you'll have to put in a full 4 Gigs of RAM to see the 3 Gigs work at all. This is a limitation of the 32 bit operating systems, not typically the hardware.

On 64-bit hardware with a 64-bit aware operating system like Vista (or Linux) you can use almost anything you can put into the machine. Most mother boards will not accept as much as the system can handle, even if the CPU is one of the first-generation 64-bit from AMD where the actual address space was not fully 64-bit useful.

So how does more RAM speed up the system?

The first way is that you can have more than one or two major programs loaded without the system "paging" extra memory out to disk. The disk is used to compensate for inadequate RAM in the machine but it is hundreds of times slower. Having enough RAM for everything you are doing to fit into without paging means you can quickly switch between word processing and spreadsheet without having to wait while the system brings the other program into RAM. It also means you can deal with larger documents or spreadsheets without having to wait when moving from the beginning to the end and back.

The second way that the extra RAM speeds up the system is called disk caching - using the extra RAM in the system to make the disk seem faster - both on reading and writing. When the system reads from disk and there is spare RAM, it will read "the next block" from a file before you or the program asks for it - and will keep doing so as long as there is spare RAM. It will also store data to be written to disk either for a few seconds (as much as 30), or until the system is less busy, then write it all out at once. Note that this can also save significant battery life if you are on a laptop.

All in all, having as much RAM in the system today is a win-win situation. It speeds up your work in several ways and it keeps you from purchasing new hardware and throwing away the old.