First of all a big " THANK YOU ! " to Netkas, Rominator, Fl0r!an Blacksheep & jeanlain for having taught us how to fish . . as opposed to giving us one fish.

And  . . . . Netkon1 for having big cohones and great soldering skills.

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NOTE : There are no flashed efi roms are not on this site. Learn how to flash PC video cards as we have, it is worth the effort at :http://forum.netkas.org/index.php?PHPSESSID=129t4km0d8luq5nhl252fohv75mkbk93&#1

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5.0 GT/s MOD for flashed AMD/ATI Radeon REFERENCE HD 5870 1 Gb video cards

for classic Mac Pro's

All Apple Mac Pro's from Apple ship with a standard ( in this case ) AMD or ATI Radeon card which has a PCIe link speed of 5.0 GT/s.

These video cards are Apple-modified cards for windows computers. Apple uses a non-industry standard boot procedure called EFI whcih allows the user - holding down the OPTION key on the keyboard at startup to select different boot configurations eg : Start in OS X Mavericks installed on a dedicated hard drive or HDD partition.

Over the past few years it has been possible to flash the ROMS of these almost identical Windows PC video cards to get to the EFI BOOT SCREEN in Classic Mac Pro's from the 1.1 to the 5,1 models.

However .. although after having been successfully flashed these cards are showing a PCIe link speed of 2.5 GT/s as opposed to a native Apple shipped card with 5.0 GT/s.

A lot of people have said that the benefit of having the 5.0 GT/2 link speed is minimal . ..  but Apple has enabled 5.0 GT/s on all recents cards . . they must have a valid reason for having gone to this trouble.

The solution appears to be either the inclusion or removal of a single ( in most cases ) resistor.

NOTE : "Reference " cards : AMD designs and releases for example the HD 5770 which other GPU companies such as Sapphire, MSI or HIS will then manufacture their own cards for retail -essentially all three companies cards will have the same layout on the PCB board though often they move resistor positions around a bit but if the card is an AMD REFERENCE card the resistors will ideally appear in the same general area on the pcb.

Sapphire, Gigabyte, MSI & HIS cards tend to be REFERENCE cards at least in their first release version.

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REFERENCE HIS iCooler HD 5870 1Gb & Sapphire Vapor-X 1Gb HD 5870 1 Gb.

NOTE : The REF Gigabyte and MSI HD 5870's will probably have the same " three pad " layout near CrossFire connector

( Use the right mosue button to download the full size pic )

On both of these REFERENCE cards there are THREE vacant pads up near the CrossFire conncector as shown in the pic below.

( Use the right mosue button to download the full size pic )

Ideally, you should connect the two pads furthest away from the CrossFire connector by soldering a resistor across them. I am still waiting for info on exactly which resistor to use.

For a quick test I used a very finely sharpened 2HB lead pencil to bridge them.

This should only be done to verify that the mod is working.

I recommend covering the top pad with sticky tape first .. and after the pencil mod. . gently blow away excess graphite. ( if you don't see 5.0 speed after booting then you need more graphite - work UP to the right level of graphite . . . . not DOWN.

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NOTE : Do a  "PRAM RESET" after hacking a card. To do this restart your cMP while holding down these keys : "P" + "R" + Apple key/Command key + OPTION key until you hear the "Happy Mac" Chime.

Done ! ( in Mavericks 10.9.5 )

OceanWave's FPS benchmarks are wrong at least in Mavericks 10.9.5  but the PCIe link speed is an accurate reprentation.

HIS HD 5870 benchmark from UNIGINE "Heaven" .

Not bad for a now old card.

After the MOD this HIS HD 5870 loaded in Sierra 10.12.6 and showed 5.0 GT/s link speed but it took a while to get to the desktop and then it was NOT LISTED under "Metal capable"

but worked smoothly in every Sierra app I tested.

All said and done the AMD REFERENCE HD 5870 cards are still useful if only as backups.

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Next up will be the 5.0GT/s mod for the reference HIS HD 7950 3Gb ( flashed )