iMac 8,1 2008 8gb ram upgrade

Hi Michael PM

Thanks for your and others contribution. May i ask what the most i can do with my machine too, as it is starting to feel a bit slow and old, like its owner? Info below

Hardware Overview:

Model Name: iMac G5

Model Identifier: PowerMac8,1

Processor Name: PowerPC G5 (3.0)

Processor Speed: 1.8 GHz

Number Of CPUs: 1

L2 Cache (per CPU): 512 KB

Memory: 1.25 GB

Bus Speed: 600 MHz

Boot ROM Version: 5.2.2f2

Serial Number (system): W844802TPP8

Hardware UUID: 00000000-0000-1000-8000-000D935A96B4

You can install a max of 2GB and would probably benefit from (if you haven't already done so) Reformatting drive and doing a fresh install I'm sure you would notice a difference with the extra 750MB.. The memory is really cheap now too

I have successfully installed 8GB of DDR2 on my 24" iMac 8.1 early 2008.

Snow leopard.

Manufacter is micron.

Did stress test and memtest86 so don't try to say that I downside to 6 or other non sense stuff.

I suspect that with 10.7 I might end up with some problems. I will check 😉

Please stay away from crucial or OWC as they sell components 2x times more expensive than market price.

There are no such think as Mac ram or bla bla and macs aren't picky.

I work as Unix SYS admin, I opened tons of macs and they all comes with ram from different manufactured.

So even mother Apple doesn't care about the ram manufactor why should u?

Uh...WRONG!

Your "advice" about this is faulty.

The reason you find different stock RAM in Macs is that Apple puts out bids to RAM manufactures to manufacture RAM specifically for Apple Computers.

LIke everything else Apple does, it is custom designed and manufactured RAM specific for Apple products and to Apple's own specifications.

It is NOT standard "off the shelf" or commonly manufactured RAM for the general computer/ Windows PC industry.

IT DOES MATTER what type of RAM goes into a Mac.

Typical standard PC RAM (like from Micron) may not be spec'd exactly as Apple has spec'd their RAM.

The usual spec issues with RAM that is problematic in a Mac and RAM that is not working well in Macs is the timing latency of the RAM.

Apple is, usually, very strict on this spec. Typical Apple spec'd RAM usually has a timing latency of 10 ms or slightly less.(usually I see 9ms listed for Apple RAM). Typical standard "off the shelf" PC RAM is usually spec'd with a slower timing latency of 11 or 12 ms.

Most of the time, Samsung is one of Apple's main RAM manufacturers/suppliers. There are a handful of others that I can't recall, at the moment.

But Apple charges a high premium for their RAM because of the custom spec'd nature of the RAM.

Both Crucial and OWC ( macsales.com) get access to these same Apple RAM suppliers/manufacturers.

But they can buy and sell the RAM cheaper than Apple because the RAM is not branded with Apple's logo or trademark.

Kingston, PNY, Micron and PC type RAM that is, also, bought and sold by Crucial RAM, too, and some of the other common "made for PC" RAM suppliers /manufacturers are NOT reliable and/or compatible in Macs.

That is fact and very well known by knowledgeable Mac users.

I was told my model:

Model Identifier: iMac8,1

Processor Name: Intel Core 2 Duo

Processor Speed: 3.06 GHz

... would only recognize 4GB RAM max, so when I upgraded the stock 2GB (2 x 1GB) to 4GB (2 x 2GB) I thought that was as much as I could put it. Now I see that 6GB is really the ceiling (and some people got 8GB to work, but only reliably in older OS versions like Snow Leopard, not so much with Mavericks). So does that mean I have to spend money on a 6GB upgrade kit that consists of a 2GB stick and a 4GB stick, or can I just use one of the 2GB sticks I already have and replace the other with a 4GB one?

That would seem to be more cost-effective if there is no technical reason not to do that (I know we are supposed to install RAM in equal pairs, but since I don't know of any 3GB RAM modules, I supposed that is not possible for this configuration). If the extra 2GB RAM would alleviate the constant slowness and spinning=beach-ball I see now when I try to do something as simple as and open file dialog or the long wait I have when waiting for my iPhotos to show up in an add photo dialog box, that would be much cheaper than the recent desire to spend another two or three grand on a new machine (although it would be nice to upgrade my puny 500GB internal hard drive too and get some USB 3 or Thunderbolt ports for external drives).

Before I advise anything to you, we need to make sure you do not have anything else in your system that maybe another cause of your Mac's slowdowns.

It would help us to help you if we could have some more technical info about your iMac.

If you like, please go ahead and download, install and run Etrecheck.

Etrecheck was developed as a simple Mac diagnostic report tool by a regular Apple Support forum user and technical support contributor named Etresoft. Etrecheck is a small, unobstrusive app that compiles a static snapshot of your entire Mac hardware system and installed software.

This is a free app that has been honestly created to provided help in diagnosing issues with Macs running the new OS X 10.9 Mavericks.

It is not malware and can be safely downloaded and installed onto your Mac.

http://www.etresoft.com/etrecheck

Copy/paste and post its report here in another reply thread so that we have a complete profile of your Mac's hardware and installed software so we can all help with your Mac.

Thank You.

Very well, it is quite lengthy, so I hope that's all right:

EtreCheck version: 1.9.15 (52)

Report generated October 7, 2014 at 4:27:19 PM EDT

Hardware Information: ?

iMac (24-inch, Early 2008) (Verified)

iMac - model: iMac8,1

1 3.06 GHz Intel Core 2 Duo CPU: 2 cores

4 GB RAM

Video Information: ?

NVIDIA GeForce 8800 GS - VRAM: 512 MB

iMac 1920 x 1200

System Software: ?

OS X 10.9.5 (13F34) - Uptime: 0 days 8:27:47

Disk Information: ?

WDC WD5000AAKS-40YGA1 disk0 : (500.11 GB)

S.M.A.R.T. Status: Verified

EFI (disk0s1) <not mounted>: 209.7 MB

Macintosh HD (disk0s2) / [Startup]: 499.25 GB (21.6 GB free)

Recovery HD (disk0s3) <not mounted>: 650 MB

USB Information: ?

AVerMedia AVerTV Volar MAX

Apple Inc. Built-in iSight

Tablet PTZ-630

Apple Inc. BRCM2046 Hub

Apple Inc. Bluetooth USB Host Controller

Apple Computer, Inc. IR Receiver

Macally Peripherals Hub in Macally ICEKEY keyboard

Logitech USB Receiver

Macally Peripherals Macally ICEKey keyboard

Gatekeeper: ?

Mac App Store and identified developers

Kernel Extensions: ?

[loaded] com.AmbrosiaSW.AudioSupport (4.1.2 - SDK 10.7) Support

[loaded] com.Logitech.Control Center.HID Driver (3.6.0 - SDK 10.6) Support

[not loaded] com.Logitech.Unifying.HID Driver (1.2.0 - SDK 10.6) Support

[not loaded] com.Maxtor.driver.PowSecDriver (4.3.19) Support

[not loaded] com.TASCAM.iokit.US122 (3.4.0f1) Support

[not loaded] com.avermedia.driver.A815 (1.2.0) Support

[not loaded] com.avermedia.driver.AF9035 (1.0.21) Support

[loaded] com.avermedia.driver.AVerDTVFamily (2.11 - SDK 10.6) Support

[loaded] com.avermedia.driver.AVerH826 (2.0.5) Support

[not loaded] com.avermedia.driver.AVerPolaris (1.0.59 - SDK 10.6) Support

[not loaded] com.caiaq.driver.NIUSBGuitarRigMobileDriver (2.3.14) Support

[not loaded] com.caiaq.driver.NIUSBHardwareDriver (2.3.14) Support

[not loaded] com.cy.iokit.Morpheus (1.4) Support

[loaded] com.eltima.ElmediaPlayer.kext (1.58 - SDK 10.4) Support

[not loaded] com.hzsystems.driver.CDSDAudioCaptureSupport (1.5) Support

[not loaded] com.kensington.mouseworks.driver.ADBID32Mouse (3.0) Support

[not loaded] com.kensington.mouseworks.driver.ADBID32MouseX1 (3.0) Support

[not loaded] com.kensington.mouseworks.driver.ADBID4Mouse (3.0) Support

[not loaded] com.kensington.mouseworks.driver.ADBID4MouseX1 (3.0) Support

[not loaded] com.kensington.mouseworks.driver.KMWBluetoothHIDMouse (3.0) Support

[not loaded] com.kensington.mouseworks.driver.KMWBluetoothOldHIDMouse (3.0) Support

[not loaded] com.kensington.mouseworks.driver.KMWUSBHIDMouse (3.0) Support

[not loaded] com.kensington.mouseworks.driver.USBMouseX1 (3.0) Support

[not loaded] com.kensington.mouseworks.driver.VirtualMouse (3.0) Support

[not loaded] com.kensington.mouseworks.driver.VirtualMouseX1 (3.0) Support

[not loaded] com.kensington.mouseworks.iokit.KensingtonMouseDriver (3.0) Support

[not loaded] com.kensington.mouseworks.iokit.KensingtonMouseDriverX1 (3.0) Support

[not loaded] com.kensington.trackballworks.driver (1.1.0) Support

[not loaded] com.macally.driver.ICEKey (1.0) Support

[not loaded] com.macally.iokit.MacallyICEKBDriver (1.0.0) Support

[not loaded] com.maxtor.iokit.IOFireWireMxBt (4.2.6) Support

[not loaded] com.roxio.TDIXController (2.0) Support

[not loaded] com.wacom.kext.wacomtablet (6.3.4 - SDK 10.8) Support

Problem System Launch Agents: ?

[failed] com.apple.helpd.plist

Launch Daemons: ?

[invalid] com.AVerMedia.AVerTV

[loaded] com.adobe.fpsaud.plist Support

[loaded] com.adobe.SwitchBoard.plist Support

[loaded] com.adobe.versioncueCS3.plist Support

[loaded] com.ambrosiasw.ambrosiaaudiosupporthelper.daemon.plist Support

[loaded] com.AVerMedia.AVerTV.plist Support

[loaded] com.bombich.ccc.plist Support

[running] com.eltima.ElmediaPlayer.daemon.plist Support

[failed] com.google.GoogleML.plist Support

[running] com.intego.commonservices.daemon.plist Support

[loaded] com.intego.commonservices.icalserver.plist Support

[running] com.intego.task.manager.daemon.plist Support

[loaded] com.macpaw.CleanMyMac2.Agent.plist Support

[loaded] com.oracle.java.Helper-Tool.plist Support

[loaded] com.oracle.java.JavaUpdateHelper.plist Support

[loaded] com.rosecrux.kjams.plist Support

[loaded] com.sharpcast.xfsmond.plist Support

[running] com.speedtools.scheduleagent.plist Support

[loaded] com.spotflux.Spotflux.tun.plist Support

[running] com.trendmicro.icore.av.plist Support

[running] com.trendmicro.icore.main.plist Support

[running] com.trendmicro.icore.wp.plist Support

[running] com.trendmicro.itis.plugin.plist Support

[loaded] com.tunnelbear.mac.tbeard.plist Support

Launch Agents: ?

[running] AVerQuick.plist Support

[not loaded] com.adobe.AAM.Updater-1.0.plist Support

[loaded] com.adobe.CS5ServiceManager.plist Support

[running] com.brother.LOGINserver.plist Support

[not loaded] com.divx.dms.agent.plist Support

[not loaded] com.divx.update.agent.plist Support

[loaded] com.intego.task.manager.notifier.plist Support

[running] com.Logitech.Control Center.Daemon.plist Support

[loaded] com.oracle.java.Java-Updater.plist Support

[loaded] com.trendmicro.itis.dca.plist Support

[running] com.trendmicro.itis.uimgmt.agent.plist Support

[running] com.wacom.wacomtablet.plist Support

[running] net.culater.SIMBL.Agent.plist Support

User Launch Agents: ?

[loaded] com.adobe.AAM.Updater-1.0.plist Support

[loaded] com.adobe.ARM.[...].plist Support

[loaded] com.adobe.ARM.[...].plist Support

[running] com.akamai.single-user-client.plist Support

[not loaded] com.ecamm.printopia.plist Support

[loaded] com.google.keystone.agent.plist Support

[not loaded] com.iLike.Agent.plist Support

[loaded] com.macpaw.CleanMyMac2Helper.diskSpaceWatcher.plist Support

[loaded] com.macpaw.CleanMyMac2Helper.scheduledScan.plist Support

[loaded] com.macpaw.CleanMyMac2Helper.trashWatcher.plist Support

[not loaded] com.plexapp.helper.plist Support

[not loaded] com.spotify.webhelper.plist Support

[loaded] com.trendmicro.itis.uninstaller.plist Support

[not loaded] com.valvesoftware.steamclean.plist Support

[not loaded] ws.agile.1PasswordAgent.plist Support

User Login Items: ?

Typinator

SIMBL Agent

Spark Daemon

OpenDNS Updater

Dropbox

MediaCentral Launcher

LOGINserver

InstUtilLaunch

Internet Plug-ins: ?

WacomNetscape: Version: 2.1.0-1 - SDK 10.8 Support

Flash Player: Version: 15.0.0.152 - SDK 10.6 Support

DivX Web Player: Version: 3.2.3.1164 - SDK 10.6 Support

AdobePDFViewer: Version: 8.2.3 Support

Unity Web Player: Version: UnityPlayer version 4.1.2f1 Support

Photo Center Plugin: Version: Photo Center Plugin 1.1.2.2 Support

googletalkbrowserplugin: Version: 5.1.4.17398 Support

iPhotoPhotocast: Version: 7.0 - SDK 10.8

DirectorShockwave: Version: 11.0.0r465 Support

QuickTime Plugin: Version: 7.7.3

FlashPlayer-10.6: Version: 15.0.0.152 - SDK 10.6 Support

AmazonMP3DownloaderPlugin: Version: AmazonMP3DownloaderPlugin 1.0.17 Support

nplastpass: Version: 3.1.21 Support

Mozillaplug: Version: 1.0

AmazonMP3DownloaderPlugin1017277: Version: AmazonMP3DownloaderPlugin 1.0.17 Support

CANONiMAGEGATEWAYDL: Version: 3.1.0.2 Support

CouponPrinter-FireFox_v2: Version: Version 1.1.9 - SDK 10.5 Support

npgtpo3dautoplugin: Version: 0.1.44.29 - SDK 10.5 Support

OVSHelper: Version: 1.1 Support

Silverlight: Version: 5.1.30514.0 - SDK 10.6 Support

LogitechHarmony: Version: 2.0 - SDK 10.7 Support

Default Browser: Version: 537 - SDK 10.9

Flip4Mac WMV Plugin: Version: 3.2.0.16 - SDK 10.8 Support

o1dbrowserplugin: Version: 5.1.4.17398 Support

WacomTabletPlugin: Version: WacomTabletPlugin 2.1.0.2 Support

JavaAppletPlugin: Version: Java 7 Update 67 Check version

Gears: Version: 1.0 Support

Safari Extensions: ?

Better Facebook (Disabled)

AllMyTube (Disabled)

Add To Amazon Wish List-1 (Disabled)

Web Snapper (Disabled)

Videobox (Disabled)

Ebates

Ghostery-2

Flint

SocialBa!

1Password

iTis toolbar for safari

Audio Plug-ins: ?

BluetoothAudioPlugIn: Version: 1.0 - SDK 10.9

AirPlay: Version: 2.0 - SDK 10.9

AppleAVBAudio: Version: 203.2 - SDK 10.9

iSightAudio: Version: 7.7.3 - SDK 10.9

iTunes Plug-ins: ?

Quartz Composer Visualizer: Version: 1.4 - SDK 10.9

User iTunes Plug-ins ?

iGoom: Version: 1.9 Dev5

User Internet Plug-ins ?

fbplugin_1_0_3: Version: (null) Support

fbplugin_1_0_0: Version: (null) Support

Move-Media-Player: Version: npmnqmp 071303000006 Support

fbplugin_1_0_1: Version: (null) Support

Picasa: Version: 1.0 Support

3rd Party Preference Panes: ?

Akamai NetSession Preferences Support

Clusters Support

Flash Player Support

Flip4Mac WMV Support

Java Support

Logitech Control Center Support

MediaCentral Support

MusicManager Support

Perian Support

Synergy Support

WacomTablet Support

Time Machine: ?

Skip System Files: NO

Mobile backups: OFF

Auto backup: YES

Volumes being backed up:

Macintosh HD: Disk size: 464.96 GB Disk used: 444.84 GB

Destinations:

TimeMachineBackup [Network] (Last used)

Total size: 3 TB

Total number of backups: 38

Oldest backup: 2014-06-14 04:51:23 +0000

Last backup: 2014-10-07 20:05:00 +0000

Size of backup disk: Excellent

Backup size 3 TB > (Disk size 464.96 GB X 3)

2TB Backup [Local]

Total size: 2 TB

Total number of backups: 68

Oldest backup: 2010-05-13 05:54:30 +0000

Last backup: 2014-10-06 23:37:16 +0000

Size of backup disk: Excellent

Backup size 2 TB > (Disk size 464.96 GB X 3)

Time Machine details may not be accurate.

All volumes being backed up may not be listed.

Top Processes by CPU: ?

13% firefox

9% Quicken Essentials

8% WindowServer

1% mds

1% AdobeReader

Top Processes by Memory: ?

736 MB firefox

721 MB Adobe Photoshop CS5

209 MB Finder

199 MB Quicken Essentials

174 MB WindowServer

Virtual Memory Information: ?

28 MB Free RAM

1.36 GB Active RAM

1.35 GB Inactive RAM

572 MB Wired RAM

1.53 GB Page-ins

53 MB Page-outs

Well,

This is as I suspected. While maxing out your RAM would be a good idea (you can, indeed, replace one of your 2 GB RAM modules with a 4 GB RAM module from OWC (macsales.com), this is NOT the source of your issues and it may not help, currently, your issues.

You have a heavily modified OS X system as well as nearly full hard drive.

Two major issues that are the main culprits of your Mac's slowdowns.

Once a hard drive gets to between 15-20 GBs of free space, it is time for some house cleaning, but even this isn't enough as your system is heavily modified, also, and this still may keep your Mac from running well.

Plus, you have some Intego and Trend Micro software install that are total crap for your Mac and unfortunate for you, you have went and installed and used CleanMyMac 2 which is well-known "garbageware" for your Mac that, probably, has already done damage to your Mac's OS X system that is irreparable.

WAaay too many Internet web plugins, etc...

You have, effectively, treated your iMac exactly like a Windows PC and there is no magic fix that is going to fix this.

Your iMac is running crummy because of the way you have been treating it!

I believe it is time for you to start your iMac off with a clean slate.

You need to invest in and purchase a fast transfer, good quality, large capacity (at least 2 TB storage size) FireWire 800 external hard drive.

Format this new drive using OS X Disk Utility app as a OS X Extended Format ( journaled) drive with GUID partition scheme and partition this drive into two equal partitions.

Then, purchase, install and use a data cloning app, like CarbonCopyCloner or SuperDuper, to make an exact and bootable copy (clone) of your entire Mac's internal hard drive.

Then use OS X Disk Utility to completely erase and refprmat your iMac's internal OS X Mavericks partition and use OS X Recovery Mode (Command-R keys) to do a complete clean reinstall of OS X Mavericks.

You will need to completely reinstall of all of your Applications and you will need the backup on the new external hard drive to manually copy over all your important,personal data.

Leave any large libraries, like your iTunes and iPhoto libraries on the external hard drive and any other large files or folder (other movie or images folders, etc....) also on the external hard drive.

On the external hard drive copy all of your inportant data and libraries to the second partition you have created on the external hard drive, because once yoy have straightened out the mess of a system on your Internal hard drive, you are going to use CarbonCoptCloner or SuperDuper to re-clone your iMacs internal hard drive system back over onto your previously cloned system partition on the external drive so you will have two new, clean OS X systems.

DO NOT INSTALL ANYMORE MORE CRAP LIKE COMMERCIAL ANTIVIRUS SOFTWARE OR APPS CLAIMING TO "CLEAN" YOUR MAC!!!

FYI

Apps like MacKeeper or any other maintenance apps like CleanMyMac 1 or 2, TuneUpMyMac, MacCleanse or anything like these apps, installed on your Mac, while they appear to be helpful, can do too good a job of data "cleanup" causing the potential to do serious data corruption or data deletion and render a perfectly running OS completely dead and useless leaving you with a frozen, non-functional Mac.

Plus, these type of apps aren't really necessary OR needed. They really aren't.

There are manual methods to clear off unnecessary data off of your Mac that are safer and you have complete control over your Mac and not just leave a piece of auto cleaning software in charge of clearing off data off of your Mac. Their potential of causing OS X issues outweighs the implied good and benefits these types of hard drive or memory "cleaning" apps are written to do.

These types of system 'cleaning" apps are very poorly written and are really a scam to rob newbie and novice Mac users of their hard earned cash for a poorly written maintenance program that will do much more harm to a perfectly normal running OS X system than the good that the app developers purport these types of apps will do.

Plus, the software companies that write these apps make it hard to easily uninstall these apps if something DOES go wrong and these apps work in a way where you have no recovery or revert function to return your Mac back to its former, working state in the event something does go wrong.

It is best to never, EVER download and install these types of apps.

The risk to your system and important data is too great a risk!

Good Luck!

Hi all, I'm new to the forum.

I'm following the thread, here it is why:

I have a 20inch iMac 8.1 (bought 2nd hand from a friend) now running 2x2gb and 10.9.5 on a 320Gb SATA.

I use it moslty for Adobe stuff (Lightroom above all, some Indesign, some AI) and web surfing.

Now it started to be very laggy.

THE question is: what's really worth the money and the effort? trying 2x4gb or moving system (maybe a clean install...) to SSD? Or even both?

I don't use the iMac for work, so I'd like it to last.

[don't ask me ram manufacturer: I don't remember it.... 🙂]

Well, as for my experience. I did order another 4GB RAM module (Crucial brand, found on Ebay for $73 with free shipping) to bring my 2008 iMac up to 6GB RAM and I followed MichelPM's advice and bought a 9pin to 4pin Firewire 800 cable on Amazon to hook up an existing Seagate FreeAgent Pro 1TB external drive that had been sitting around unused with my old 2008-2009 Time Machine backups and erased and partitioned it, cloning my internal drive with Carbon Copy Cloner and then reinstalling a clean Mac OSX Mavericks via the command-R recovery mode. When it came time to migrate my files to the new install, I only moved documents and kept my large music, photo and video libraries stored on the external drive, giving me over 350GB of free space on the internal 500GB drive.

So far, the extra RAM and clean install seemed to have made the old iMac speedier than it was and I don't see the spinning beach ball nearly as often. Apps like Photoshop seem to open faster and though I still see a delay of about 20 seconds when I try to view my iPhoto library from an "open file" dialog box, that is much faster than the even longer delay I used to experience. Having to turn on an external drive (or leave one on and hear it spinning up and down all the time) when I want to work with my music, photos or video libraries is kind of inconvenient compared to having it all on my startup drive, but I may see about putting an existing 120GB internal SSD into an external dock to see if that is a better solution.

Overall, since I had an external drive already, I probably spent only $85 total on the upgrade (and all the time to move the files around and reinstall so many things, including apps from clean installs) so I think it was worth it for the increased usability I achieved on this old model iMac compared to dropping another $1K to $3K on another machine that would NOT have things like an optical drive built into it any longer (although USB 3 and Thunderbolt ports would be nice to have for faster data throughput.)

Your reply to Mende: It shows 8gb memory status ok

Of course: this line in SystemInformation just tells what is installed, not how much is really used. On your iMac 6GB is the max that is used (addressed).

I also had significant speed issues with my iMAC 11.2 after upgrading to Mavericks.

I installed 16GB (2x8GB) DDR3 1333 Upgrade Memory Module for iMac 11.3 (i5 & i7) 12.1 12.2 from Macmemory.net, but the machine freezes after the apple Logo appeared. Any recommendations?

Thanks

Paul

Model Name: iMac

Model Identifier: iMac11,2

Processor Name: Intel Core i3

Processor Speed: 3.06 GHz

Number Of Processors: 1

Total Number Of Cores: 2

L2 Cache (per core): 256 KB

L3 Cache: 4 MB

Memory: 4 GB

Processor Interconnect Speed: 5.86 GT/s

Boot ROM Version: IM112.0057.B00

SMC Version (system): 1.64f5

Serial Number (system): QP041172DAS

Hardware UUID: 6636630C-7034-58D6-8D26-CD230E91B

Make sure all the RAM modules are seated in their respective slots.

If still issues, return the memory and purchase from these suppliers only.

Correct, compatible and reliable Mac RAM can be purchased from online Mac RAM sources Crucial memory or OWC (macsales.com).

Is anyone using Yosemite after upgrading their 2008 iMac to 6gb or 8gb of ram? Wondering if Yosemite handles the 8gb of ram. Also curious how it runs with 6gb. Any noticeable slowdowns compared to Mavericks?

I have Yosemite running on a number of early 2008 iMacs (2.66GHz) in only 3GB.

They cope with it OK, but I would not ask them to do too much -currently these machines are used to collect seismic data and push it over the web -nothing too arduous. If you ask them to do more on top of this, they start to get a lot slower, which is more of an issue, as we use the same devices to host displays.

They ran 10.8.5 very happily, and seem OK in Mavericks, but Yosemite (10.10.0) certainly feels "busier"

Was reading this to see whether I could increase performance by adding more RAM, and it looks as though swapping the 1GB module for a 4GB module will do this.