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The mystery of Mac GPUs? new HD 4870 mac vs. PC specs

Last response: in Graphics & Displays
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June 1, 2009 12:18:47 AM

*Sigh*

I'm pretty sure this is a rather taboo subject around ATI and Apple. Also on the surface this question sounds a bit silly, as asking about the use of a Mac for gaming is rather counter-intuitive, but i must assure you i'm not an idiot!

OK, that said:

I'm working with a dual quad-core 3.0 ghz Mac Pro with 8gb of RAM. Thus far i've been using the Apple version of the Geforce 8800 GT which has worked swimmingly. All this is for use with Final Cut and After Effects, etc.

GPU aside, its also about as solid as any gaming comp you could ask for. 32 bit XP could utilize one quad-core and 4 gigs of ram, and now i'm seeing that windows 7 can use both CPUs and all 8 gigs. HOWEVER! I'm still stuck with the 8800 GT, which simply doesn't cut it anymore.

My original plan was to just buy a windows card for use exclusively with Bootcamp, and switch the power cables when i used one or the other. Tedious, but worth it IMO as i'm getting 2 comps for the price of one. I was planning on getting the Radeon HD 4870 1gb and running it along with the GeForce, but ATI has since released an Apple version of the 4870 (512mb) for the Mac Pro, which seems a far more prudent decision.

Benchmarks with the mac v. of my 8800 GT in bootcamp have been identical to the PC benchmarks ive seen online, so obviously there isn't much of a performance difference between the two.

So my questions are:

What the hell IS the difference between the Mac and PC versions of a card? I'm beginning to believe it's just an arbitrary software restriction seeing as the Mac version runs perfectly in windows, but i'm assuming it would not work the other way around. Is there anybody here as foolish as me to have tried using a windows card in OSX?

In regards to my purchase, i can either get the Mac HD 4870 which will obviously work on both OS's and therefore be a more logical purchase, but also at $350 a much more expensive one.

For the same price i could get the 4870 X2, or a number of other equally sexy cards for use exclusively with windows. This would only benefit my gaming side, and i'd feel a bit guilty because of that, but its quite alot of power.


While i'd obviously be benefiting from an OSX-card upgrade for motion graphics, etc, i'd also be paying a pretty shocking price write-up, which is probably balanced by the advantages of a purely windows based card for gaming.

So, were you in as superfluous position as I, what would you do?
Any advice would be appreciated, in addition to any info on the subject of mac versions of cards.

Cheers!

ps: sorry for any redundancies in this post, thanks!
June 1, 2009 12:42:01 AM

I don't think putting two gpu's in and unplugging one will work. Reason being most xfire/sli motherboards require that if you're running with a single card that it be placed in the top slot. Placing a card in the top slot & unplugging it will usually produce errors. You could try sli 8800gt's in windows if you have a sli motherboard, I dunno if mac supports sli.

If you do try to use two graphics cards with one unplugged, you'll want to call tech support before choosing the motherboard and verify that you can put the first card into any of the available pci-e slots. I don't know if any motherboards exist that'll let you, but I don't know that they don't either.
June 24, 2009 4:53:57 PM

The difference between the MAC and PC versions of the ATI card are few.. VERY few. In fact there are only two.

#1 is the Apple Tax!, of course Apple wouldn't sell anything for their computers and not get anything out of it.. HUGE mark up on video cards makes them more money. The MAC version is $420 in canada directly from Apple, and the PC version (with 1gb of RAM mind you vs 512mb on the MAC version) will run you about $180 on sale.

#2 is the special EFI BIOS that enables the MAC Pro to recognize the card when inserted.

Now physically the cards are identical, both using the same RAM, same GPU, with minor changes on the MAC side to make it fit better into the MAC Pro case, most cards even use the SAME BIOS! So the PC version will work perfectly fine in the MAC Pro. By now you may be asking yourself, how the heck can I make the PC card work inside the MAC so that both MAC OS and Windows sees the card.. the answer is simple, find someone who has the MAC card, stuff it into a PC and clone the BIOS using free software available on the internet, then buy the PC version of the same card, (not sure if it'll work with the 1gb version, may only work on the 512mb. You may have to be brave and test it out) and use the same program that cloned the BIOS from the MAC version onto the PC version.

Sometimes this is tricky because the PC card BIOS has to support the size of the MAC BIOS, (because of the EFI information it makes the BIOS file larger than a PC version which doesn't include the EFI info.) As long as it'll fit into the BIOS you can flash the BIOS with the MAC file and it will work like a charm.
There are a few good sites that even provide you with copies of the BIOS files so you don't have to do any extra work hunting down a card to clone. Many people have used this work around for the previous MAC cards, including the ATI X1900 and the NVIDIA 8800GT. I myself have cloned an 8800 and even tweaked the GPU speed to get a little extra performance boost. ;) 

Have fun and good luck.. oh, and be careful not to fry your BIOS as this will void your warranty. :p  But chances of that happening are pretty slim, I just like to warn people ahead of time.
October 11, 2009 7:17:23 PM

I have both version of the 8800 GT, one for PC and one for Mac Pro... the difference is the instruction set in the card firmware and the BIOS for Mac... The Mac version is a superset of the PC version (e.g. the Mac card will work in the PC but not the inverse)... I haven't gotten an ATI 4870 yet but many if the PC games work well under a Windows VM (I use Parallels) unless they are really graphics intensive (Crysis, etc.)
j
!