UnintegratedCircuit
RAM Upgrade
Asus EEE PC 901 RAM Specs
Straight in with some of the numbers then: from factory, the EEE PCs of the era seemed to come with a 1GB SODIMM stick of DDR2-400 manufactured by Adata. Take this claim with a pinch of salt, however, as I have a sample size of two machines to draw from (the 901 starring in this series, and a battered old 900 as my sacrificial lamb). Just quickly then, what do all those terms mean?
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SODIMM - This is the physical form factor of the RAM. Basically all laptop RAM is Small Outline, hence the 'SO'.
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DDR2 - Think of this as the 'generation' of the RAM, more modern machines have DDR3, DDR4, etc. The 'DDR' portion simply stands for Double Data Rate, although this detail is not really important from a user's perspective.
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1GB - This is the capacity of the RAM, basically the bigger this number is, the more programs a computer can 'juggle' in the background whilst still maintaining good performance. Trust me, 1GB was not exactly generous even back then.
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400 - This is the clock speed for the RAM in MHz, so 400MHz in this instance. Basically a bigger number means more throughput and faster access times and all that good stuff.
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So with that out the way, hopefully it is obvious why a RAM upgrade is a good idea. The next question then: what can it be upgraded to? Well, after a quick search through the schematic of the motherboard, and a subsequent peek over at Intel's​ spec pages for the CPU and Northbridge chipset, the best RAM that can be used is 2GB of DDR2-533. It should be noted though that DDR2-667 is definitely supported as both of my 901s have that installed, I have no idea whether higher speed RAM sticks can also be used though, and even if they can, the additional speed will not be utilised.
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To optimise things further, you would have to delve into documentation that discusses access times and latency, and find the 'fastest' stick of RAM in that respect, although how much performance gain could be had at such relatively low frequencies, I do not know... Nor could I find said documentation. I simply opted for a 2GB stick of DDR2-667 by Crucial since it's an established brand and a seller on eBay happened to be listing them NOS for something like £4 delivered.
Swapping The RAM
Swapping the RAM is super easy in the 901. The RAM is located behind the maintenance hatch on the bottom, which is only held in by two crosshead screws - everything else is a simple push-fit.
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1) The first step, as with any computer tinkering, is to remove as much power as possible as quickly as possible. This means unplugging it, and removing the battery. For the 901, the battery is retained by the two sliders circled in red; push them outwards. The right hand one will 'click' into the unlocked position, whereas the left slider is spring loaded to return to the locked position. Both sliders must be held in the unlocked position to slide the battery out. The battery slides out from the 'top' as viewed in this picture.
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2) Now, with the battery removed (note the right slider now shows a red dot indicting it is in the unlocked position, as underlined in cyan), unscrew the two crosshead screws (size PH1) circled in red securing the maintenance hatch. I am not 100% sure whether these are captive or not, they appeared to be on this particular machine, so do not stress if they fail to come out completely - they will 'click' once they are free of their threads. Once loosened fully, dig a fingernail into the recess between the screws and pull the hatch off. It may be held in somewhat by some plastic clips, but it will come off.
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3) With the maintenance hatch removed, a series of compartments are revealed. Towards the bottom right is where the RAM is located, as highlighted by the red rectangle. This is covered by a sheet of black plastic, which in the photo is being held up to expose the RAM stick underneath. Getting hold of the plastic sheet is a little irritating since access is limited and it is rather springy - a screwdriver may help to catch hold of it before pinching it between forefinger and thumb as I am doing here.
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4) Zooming in on the RAM (and my thumb), two levers can be seen circled in red, one on either side of the RAM stick. These are what holds the RAM snugly in the socket - they simply bend outwards to release the RAM. Push them outwards with your thumb until they 'click' free - the RAM should spring up once both sides are released.
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5) And here is one I prepared earlier. Notice the shadow now under the RAM, underlined in cyan, as it is 'popped up'. The next step is to simply pull the RAM towards you at the same angle it is resting at and it will slide out smoothly. This is best done by holding it at the front corners between thumb and middle finger so as to minimise touching the black RAM chips (and also encourage gentleness). Having said that, this particular stick was actually completely dead which made this upgrade all the more worthwhile.
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6) And finally, here are the old 1GB Adata stick (top) and new 2GB Crucial stick (bottom) next to one another for comparison. I have underlined the important numbers on the labels in red (capacity, frequency, and generation).
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7) Installing the new RAM stick is, as any Haynes manual will tell you, the exact opposite of removal - although obviously you want to be installing the shiny new stick of RAM, and not the old slow one that has just been removed. A helpful tip when reinstalling the screws is to turn them anti-clockwise (as if you were undoing them) until you feel them drop into their threads, at which point they can be tightened as intended. This is not so important here since all the screws have metal inserts with threads; however, when screwing directly into plastic, this helps prevent the screws from being cross-threaded, so it is a good habit to get into.
Wrapping Up
So there is my first proper photo tutorial on how to do something, and hopefully this is a good starting point for other potential EEE PC 901 modders who perhaps have not dived into ripping up a laptop before. Or even if this is a faithful companion in need fo a new lease of life, and you have no intention of recreating the other crazy modifications I have planned, I hope this has served you well.
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