How to overclock or reclock 8800GTS for Mac Pro

[Chocomonsters]

For those of you who are using 8800 GTS instead of non-apple 8800 GT, you can use NiBiTor to reclock your 8800GTS back to its factory higher clock speed and increase voltage back to factory firmware level without using software/registry overclocking (ie, RivaTuner). This way you dont even have to use RivaTuner (although it is great program if you want to overclock your card beyong factory overclocked speed or reference speed). But most importantly you can change back your card's voltage from 1.1V back to 1.15V.

You need NiBiTor 4.0, 8800GT32.rom (from this forum), and most recent Nvidia beta driver.

1. verify 8800GT32.rom checksum (under Adv. Info tab) before you start. Ignore integrity red warning as that is from different file size due to OSX EFI which you need to boot OSX

2. change Device id from 0602 to Nvidia PCI-E 8800GTS G92 (0600) under main screen

3. under clockrates tab, enable change amount of active performance levels. recycle levels from 0 to 4 to enable "extra" row. Enter your card's true core, shader, and memory speed from factory. Put 0 for all 3D, Thrtl, and 2D. Mine was 678 core, 1728 shader, and 972 memory.

4. Under Tools select voltage table editor, change entry 1 to 1v, entry 2 to 1.05v, entry 3 to 1.1v, and entry 4 to 1.15 v

5. Under Voltage tab, change "extra" under exact mode to 1.15v. VID mode should automatically change

6. Under temperature tab, fanspeed column should now automatically have 100% for extra, 3d, thrtl, and 2D. If not put 100%.

7. open "fanspeedIC" under temperature tab. Fill into match your original 8800GTS firmware setting. Mine was TCirt = 83, min Duty cycle= 37. Rest were same as 8800GT

8. Save. and done. Just dont change Sub Vendor ID, Sub System ID, Board ID. Otherwise your card wont boot under OSX

If you want to overclock higher speed, you should experiment with RivaTuner before overclocking with firmware.

 

[tobyg]

Maybe this would fix the problem with the 8800 GTS I had with the fan not ramping up properly. Too bad I returned it. Maybe I should buy another 8800 GTS.

So NiBitor supports the Apple 8800 GT 32bit firmware now huh? Nice.

 

[Chocomonsters]

NiBiTor doesn't support it yet, meaning program doesn't recognize it as 8800GTS when it has Apple 8800 GT firmware. I dont expect next version for awhile.

But NiBiTor can change this card's clock speed just like any other G92 chip. Just needed to figure out what can be changed and what can not be changed.

Just make sure you have most recent beta driver as older driver doesn't do too good job of recognizing the card.

Most program and OS will still consider the card as GPU 0602 (ie, 8800 GT)

If your card is successfully flashed to 8800GTS, GPU-Z will show corrected Default clock speed (whereas software clocked card will still show 8800GT clock speed under default clock)

I have enclosed modified 8800GT firmware I am using and original EVGA 8800 GTS KO firmware. You can take a look with NiBiTor. IF YOU ARE GOING TO FLASH YOUR CARD, MODIFY YOUR OWN FIRMWARE. I am dont want to be responsible if you decided to use mine.

 

[Frozonecold]

NiBiTor doesn't support it yet, meaning program doesn't recognize it as 8800GTS when it has Apple 8800 GT firmware. I dont expect next version for awhile.

But NiBiTor can change this card's clock speed just like any other G92 chip. Just needed to figure out what can be changed and what can not be changed.

Just make sure you have most recent beta driver as older driver doesn't do too good job of recognizing the card.

Most program and OS will still consider the card as GPU 0602 (ie, 8800 GT)

If your card is successfully flashed to 8800GTS, GPU-Z will show corrected Default clock speed (whereas software clocked card will still show 8800GT clock speed under default clock)

I have enclosed modified 8800GT firmware I am using and original EVGA 8800 GTS KO firmware. You can take a look with NiBiTor. IF YOU ARE GOING TO FLASH YOUR CARD, MODIFY YOUR OWN FIRMWARE. I am dont want to be responsible if you decided to use mine.

If I buy the same video card as you have, I should not have a problem though.

 

[Yarrow]

Unfortunately, that approach doesn't work with my eVGA 8800GTS card (512-P3-E841-AR, _not_ KO). Everything is OK under Mac OS X, but the card became unrecognisable by nVidia's driver under WinXP. I tried to flash card with both firmware modified by myself, and firmware attached by Chocomonsters. Result was the same.

 

[Chocomonsters]

Yarrow,

can you post your original firmware from 512-P3-E841-AR?

 

[Chocomonsters]

I am triple booting my Mac Pro with OSX, Vista 32 and XP 32 with 8800GTS and 7300GT. I've installed 175.70 driver for both Vista and XP before flashing. After flashing, both 7300GT and 8800GTS were recognized by Vista 32 and OSX. Under XP, 7300GT was working as expected but 8800GTS was booted but had black screen. After reinstalling 175.70 driver for XP, it was booted and recognized fine.

Can you try to reinstall Nvidia driver for your XP? http://downloads.guru3d.com/ always has most updated Nvidia driver (beta linked to Nvidia ftp).

 

[Frozonecold]

If I overclock the Nvidia 8800GTS back to its original clock speed would OSX still use it at the lower clock speed?

 

[Chocomonsters]

I am pretty sure it will be default 8800GT 600 / 1500 / 900 speed since Nibitor doesn't even access EFI portions of firmware.

I am not sure how to verify this in OSX. If someone can tell me I can look. I am rather new to OSX. I will be more helpful on Vista / XP side

 

[Yarrow]

Yarrow,

can you post your original firmware from 512-P3-E841-AR?

Here you are. Original BIOS of eVGA 8800GTS 512-P3-E841-AR and modified one.

I have tried again with 175.70 beta driver and it works. Thanks!

 

[Chocomonsters]

Yarrow,

I am glad it worked out for you.

Just wondering, why you didn't increase base fan speed from 30% to 37%. How is your card running with higher clock and lower fan speed?

I am using default 8800GTS KO clock and fan setting.

Using RivaTuner to clock it to 750/19001/991 with fan speed of 60% for gaming. Runs pretty much all games (not sure about Crysis which I dont have) in 1920 x 1200 with max setting without any problem.

 

[Yarrow]

Yarrow,

Just wondering, why you didn't increase base fan speed from 30% to 37%. How is your card running with higher clock and lower fan speed?

30% fan speed is a default setup for 512-P3-E841-AR, that valie is obtained from the original firmware. Ckock speed i have used is default for 512-P3-E841-AR as well.
Card just running well.

 

[achaiah]

Awesome guide Chocomonsters, thanks! I flashed my EVGA 512-P3-N841-AR (yes, 'N' not 'E' as above) with an edited 8800GT ROM (for Mac) and everything worked.

A couple of tips for others who might want to try it:

1. I used UBCD to boot into DOS. I downloaded their ISO, expanded (unzipped) using 7zip and added nvflash directory (with nvflash and my edited 8800GT ROM) to the "dosapps" directory. Then you can create an updated ISO from "tools/ubcd2iso".
2. Since the Mac Pros don't boot well from USB I simply burned the ISO to a CD-RW (you can burn to a plain CD as well).
3. For easy booting I used RefIT-- it does a great job of recognizing the linux boot CD. Also, on the boot CD there are a couple of DOS boot disks, I would recommend using the OpenDOS one (with default options).
4. Read this post before swapping in your 8800GTS video card as it explains a few hiccups that can happen with hardware

 

[Chilz0r]

Can you do this with the 64-bit ROM?

 

[achaiah]

No, the vid card needs to have a 128K ROM.

 

[DickVanPaiton]

Can i follow this tutorial for my Hackintosh PC too? I have a 8800GTS 512 (same eVGA Card as Yarrow) and it works in Leopard with QE/CI but other with 8800GTs have better scores in the benchmarks.

Edit:
Did it and works! Which driver do you use in Bootcamp Vista64? Found none that worked yet :-( and 175.70 beta has no cuda support so i did not try this one.

 

[MacVidCards]

Does anyone have any ideas where the clock speeds and memory timings are in the EFI portion of the ROM?

Would enable 9800GT as well as 8800GTS for existing Macs...maybe more options.

 

[studiostefan]

how about 320 g80?

Will this work with 8800gts 320? I've searched all over for a solution on how to install it on my mac pro. This is the closest i've got.

The machine in question is an 8 core 3ghz 2008 mac pro.

I realise its an old thread, but I have to try.

Thanx.

 

[MacVidCards]

If you mean 320 Meg version...it is a G80 based card and there is no ROM written for it.

It is likely that one could be written (using Quadro FX5600 EFI as base) but sadly doubtful that anyone will.

The only 8800GTS cards that are easily flashable are the 512 Meg boards which are based on G92 chip, just like the Apple 8800GT.

 

[jons]

Maybe this would fix the problem with the 8800 GTS I had with the fan not ramping up properly. Too bad I returned it. Maybe I should buy another 8800 GTS.

So NiBitor supports the Apple 8800 GT 32bit firmware now huh? Nice.

Is there enough of a performance difference between the 8800gt and the gts to be worth it?

 

[achaiah]

Is there enough of a performance difference between the 8800gt and the gts to be worth it?

I'd say yes. The 8800GT is an older generation chip running at slower speeds. The GTS is the same chipset as GTX but at slower speeds. It supports a decent amount of overclocking though so you can get GTX performance.

 

[MacVidCards]

I'd say yes. The 8800GT is an older generation chip running at slower speeds. The GTS is the same chipset as GTX but at slower speeds. It supports a decent amount of overclocking though so you can get GTX performance.

Actually, as part of The Never Ending Name Game....there are 2 very different 8800GTS cards.

The G80 based cards come in oddball sizes like 320 Megs and 768 Megs (due to oddball RAM bus width). There is currently no way to run these in a Mac Pro but it is likely that a ROM could be made from Quadro 5600 ROM. (also G80)

The G92 cards are all 512 Megs. These can run the 8800GT ROM, to some extent. They can be clocked up from 8800GT speeds and in theory have a greater number of rendering pipes. (I am not convinced they work with 88GT ROM)