27" Late 2009 iMac GPU upgrade (working, kind of)

[exploradorgt]

Long story short, I had good luck replacing my Radeon HD 4850 with the Nvidia Quadro 1000 - 2GB, originally installed on a PC laptop running Windows, it's an old computer. To my understanding, there are diff versions (green, blue and red PCB), due to lots of (often confusing) info around the web, I'm not sure about the differences, I mean... on some pages someone says something, on other websites something different, etc.

Anyway, it works without any modification as long as you run Windows (I'm running Windows 10).

I just bought 2 cards, the Nvidia Quadro 1000M and the AMD HD 6770 to test my luck, but after seeing the many things I had to do, I just decided to TRY out of the box to see what happened. Both cards come from old laptop Pcs.

• 😌 With the HD 6770 installed, the iMac refused to turn on, no boot at all.
• 🙃With the Nvidia Quadro 1000 it booted just fine with black screen, around 40 seconds later Windows logo appears booting up, sometimes it takes 40 seconds, sometimes it takes 1 minute.

Already had Windows 10 on my SSD (placed on a DVD caddy). First, it got stuck, second boot went fine, the screen resolution was very low, but to my surprise while checking the configuration, the Nvidia Quadro 1000 made it at full resolution (2560x1440) using the Microsoft Basic Display Driver. Tried installing the Nvidia Drivers but had no luck on first attempts (no errors), but later it worked, then the screen blinked switching to the new driver, reboot, and it works just fine. I have full acceleration, brightness and contrast works only via the Nvidia Catalyst app. The machine runs just fine, fast.

In short, as long as you are fine running Windows, at least with the Nvidia Quadro 1000 you don't need any modifications, just install and go.

The card is SHORTER than the original HD 4850, one of the electronic pieces doesn't fit the heatsink, so I had to grind it with my Dremel, placed it with thermal paste and done. The memory chips aren't a perfect fit for the heatsink and only half of each chip fully reaches the metal, the rest makes no contact. I just wanted to try and explore before doing any further modifications.

To my surprise, I don't see any overheating (checking with thermal sensors and my fingers).

The Core i5 CPU does gets hot, but I guess it just didn't like me replacing the thermal past, so I will have to do it again.

So far, I went from 512MB of video memory to 2GB, full acceleration and sleep/wake functions, everything working just fine.

* Edited to specify Quadro 1000M (not just 1000).

 

[Procrastinus]

The memory chips aren't a perfect fit for the heatsink and only half of each chip fully reaches the metal, the rest makes no contact.

One can always use some 1mm thermal pad to ensure full contact. See here for some information - different but similar card used.

 

[exploradorgt]

One can always use some 1mm thermal pad to ensure full contact. See here for some information - different but similar card used.

Thanks, I found and checked that page in the past, quite detailed and helpful.

My case is a bit interesting... not perfect, it's just... at the time of testing the Quadro 1000m I was a bit tired of tearing down the computer and putting it together over and over, so I just placed the GPU there to see if it booted, seeing it did, proceeded to put everything back together just adding thermal paste to the GPU chip only, didn't worry about the memory chips because I thought "this is just for a tiny bit of time while I perform some tests".

Surprisingly... after several tests I found out this new graphics card doesn't get hot as the original HD 4850, not even near!!!, it stays fresh to the touch on both sides. The HD4850 had only 512MB or vRAM, but this new Quadro 1000m comes with 2GB. I know I'm taking my chances, but so far so good, working perfectly.

During my research, found lots of information, sure many people said you have to cover the memory chips to allow cooling via the heatsink, but also found people saying "don't" cover the coils or it will fail (regardless of using thermal paste or thermal pads). I can understand why the coils shouldn't be covered, cooled? yes, but separately, they generate heat on their own, trying to cool them with the same heatsink will only feed them heat, probably more than they produce themselves. So, honestly, my card is working fine while only having thermal paste covering the graphics chip, and it stays cool. I'm not saying it's the best proved method or that everyone should do it, no, just reporting and sharing. I will surely report in the future of any issues.

So far, I can specifically confirm the main source of heat on my 27" 2009 iMac it's the LCD and the PSU, it's the top left what ends hot, hotter than the top right.

 

[Nguyen Duc Hieu]

Quadro Q1000m has 45W TDP, HD4850 perhaps have at least 75W TDP.
Your iMac will be less stressed on thermal aspect.
2GB of VRAM is redundant, and helps relaxing the GPU more => much cooler.
And you are using the heatsink designed for 75W TDP on a 45W GPU.

 

[exploradorgt]

Quadro Q1000m has 45W TDP, HD4850 perhaps have at least 75W TDP.
Your iMac will be less stressed on thermal aspect.
2GB of VRAM is redundant, and helps relaxing the GPU more => much cooler.
And you are using the heatsink designed for 75W TDP on a 45W GPU.

that's quite relieving