Mix and match SLI with ALL Y series GPUs (650m, 750m, 755m) might be possible!

I posted this on another forum, and thought it might be useful here since rumors are flying around about the availability of the various ultrabay gpu models. I know the 15.6" and 14" models of the 650m ultrabays are in circulation right now, but the others are as of yet uncertain. Certainly, there will be some configurations that end up with the short end of the stick, but it's not a total loss.

I've been going with some trial and error with my 650m ultrabay card, and have concluded that for SLI to work, the two cards have to be reporting the same device ID. That is determined at the hardware/firmware level of the GPU. It can't be modified with BIOS, even if you flash a 750m BIOS onto a 650m (which i did successfully). However, what's more important for SLI functionality may be at the driver level. If the DRIVERS/operating system can see/report both cards as being the same, SLI should work. More specifically, if you can trick the Nvidia drivers into treating a 650m and a 750m as the same card, it should open up the SLI feature. We know this would work on a hardware level because the two cards use the exact same chip, same number of shaders, memory, etc. The only differences are the clocks, but those can be modified any number of different ways quite easily. SLI will physically work with any of the cards in this laptop series, we just need to get around the device ID/SLI check issue.

So, in my search for a solution I came across this website:

SLI with different cards - techPowerUp! Forums

This guy put together modified driver versions that apparently ignore mismatched device IDs and might allow two same-chip cards to work together in SLI! Most cards that are of the same chip but different names seem to work together with this method. Different chips are hit and miss. I think it would be extremely useful if we could get together and test this out. Unfortunately, I have a 650m system and there are no 750m ultrabays I can use to test this out. However, if someone with a 750/755m system could try it with a 650m ultrabay, we might have wa working solution in the absence of one or more ultrabay models.

***I should also note, I've heard of people with the 750m putting 650m ultrabays into their laptop, and saying that the laptop wouldnt allow it to boot up the OS, as if the card were subject to a whitelist. I believe that'd easily be avoided with Svl7's modified/unlocked BIOS from the techinferno forum. Unfortunately, this means a BIOS mod is required to get this working, but I think that's a small risk to take.


****EDIT****

Thanks to EmberV, we now have a patch for the latest Nvidia drivers! Confirmed working for mix-match SLI, though not specifically for 650m and 750/755m yet.

DifferentSLI 327.23 x64

 

So you're basically saying i can just buy a 650M bay, install a modded driver, and then have it SLI with my 750?

I'm already running Svl7's un-whitelisted BiOS, so putting a 650m in probably will not result in any errors.

Could you link to the thread in TechPowerup? Thanks.

EDIT: http://www.techpowerup.com/forums/showthread.php?t=158907

Honestly, if anyone can test this and get it to work, I *Will* buy a GN35, that is 100% guaranteed. Best of all, i won't have to deal with shady Chinese people!

You can get it here for a low price (united states):

http://www.pcconnection.com/IPA/Shop/Product/Detail.htm?sku=15722794

Still looking for a Canada reseller.

 

Changing the device ID is certainly possible. Check out this post where it was discussed how to change a desktop GTX 690 and 680 into its Quadro and Tesla counterparts: [MOVED] Hacking NVidia Cards into their Professional Counterparts - Page 1

It may be possible that similar straps exist on the GN36 card, or it could just be as simple as a VBIOS mod. More research would be required. If the GPU's are in fact the same chip with just different device IDs, then there is no reason why this should not work.

 

I don't think it is about changing the ID's of the devices, but rather allowing a driver to SLI the cards without having to change ID's. Both cards are GK104's with the same shaders, etc. So i don't see why this wouldn't work.

Hacking the GeForces into Quadros is another story, and bottom line, if anyone figures out how to do it, Nvidia will *not* be happy. And, Lenovo would be angry as the Y510p would essentially destroy the W530 in terms of workstation performance

 

I'm just saying that if you changed the device ID it may circumvent the need to mod the driver files. I mainly just don't want to have to enable testsigning mode because of the patched drivers signatures being broken.

Took a look at the GT750M and GT650M vbios files using the KGB vbios modding tool. The device ID for GT750M is 0FE4 and the device id for GT650M is 0FD1. It may be as simple as a hex edit and KGB checksum adjust to allow this card to be used. I don't have a GN35 card so I can't test.

 

Why not just cancel the TaoBao order, grab a GN35 from an American retailer and use that? You would save ~200$.

Also, why not just mod the Vbios of your soldered 750M see if it registers as a 650M?

 

Found the GN35 in Canada:

Agile Electronics - Buy Mfgs Part-#:0C22230 online in Canada

Only problem is that they don't ship to my province (PEI). What the FU-

 

Can't cancel once it's ordered with the agent and I don't want to brick my BIOS as the VBIOS is contained in the actual BIOS.

With NVIDIA's track record with desktop cards, it used to be as easy as just changing the device ID in vbios and flashing it. With Kepler, they added the hardware straps to calculate the device ID. I don't know if they are doing the same with the laptop cards. I guess it doesn't really make sense for them to do it with an product that is not sold directly to consumers.

 

Anyways, i'll be calling 'novo tonight and i might order the GN35. If it works with the modded driver (i will not be vbios flashing) i'll keep it otherwise i'll just return it.

Apparently no retailer ships GN35 to PEI, Canada, so ordering from Lenovo will be required. Yay for 2-3 weeks of shipping!

 

Did a quick VBIOS mod.
From left to right
GT750M - GT650M (unmodded) - GT650M (modded)

I don't think the name or the board value matters.

 

So what does this translate to?

All GPUs are the same and can all be SLI'd with proper BIOS mods?

 

Just showing that you could change the device ID in vbios. If it flashes and shows up, then great. I can't test obviously, so we would need someone that can and is willing.

 

I'm just scared of bricking something, and then having 150$ go down the toilet.

 

That is the risk one would have to take with something like this. Obviously a driver mod works too, it would just be "cleaner" if this way worked without having to have testsigning mode and have to mod every new driver that comes out.

 

On top of that, non-windows support like Linux would be fine.

I'll order the GN35 tonight, or see if i can. Depends on the price.

 

I have already tried flashing a 750m BIOS onto a 650m. It requires you to ignore several ID mismatch errors with nvflash using the -4, -5, and -6 options, but the result is nothing more than a conversion to the 750m clock and voltage settings. The device ID remains unchanged, even though the BIOS has the 750m device ID in it. To the best of my knowledge, changing the device ID would require modification of the software straps in the least, or modification of the hardware straps at the worst. However, as you mentioned, the device Ids only differ by the last two entries, so there's a good possibility it could be changed in the firmware alone.

 

Seeing that it works with the GT750M vbios sounds good so we can have matching clockspeeds, but it sounds like we would have to modify the hardware straps. Can you get a picture of the GN35 PCB? We should compare it with the GT750M5 PCB for the y510p (since we don't have a GT750M4 for the y410p yet) to see what has changed on the PCB layout.

 

I can tell you that the 14" and 15.6" ultrabays will be the exact same GPU and Device ID, so as long as you have a 750m it'll be a good comparison. I will try to get a picture of my 650m this weekend.

 

Okay, so i'll order my GN35 this weekend! Wish me luck!

Any recommendations on retailers? I'm planning on calling Lenovo first, but i am also expecting Lenovo to be out of stock. Please be sure that whatever retailer you recommend can ship to Canada.

 

Since I will be getting my GT750M5, guess I will contribute some PCB photos when it gets here.

 

Bad new guys.

Apparently, DifferentSLI only supports the following drivers:
290.53 Windows Vista&7 x64
296.10 Windows Vista&7 x64
301.42 Windows Vista&7 x64
310.70 Windows Vista&7 x64
314.22 Windows Vista&7 x64
320.18 Windows Vista&7 x64

Unfortunately for us, after trying all of these drivers, none of these supports GeForce 7xx.

Looks like that 650M will serve as an (expensive) physX card ahaha

 

I will check his patch to see what it changes and see if it can be updated for the latest driver.

 

The drivers that the 750M supports are:

GeForce 331.40 Driver BETA
GeForce 327.23 Driver WHQL
GeForce 326.80 Driver BETA
GeForce 326.41 Driver BETA
GeForce 326.19 Driver BETA
GeForce 320.49 Driver WHQL
GeForce 320.49 Driver BETA
GeForce 311.54 Driver LENOVO CUSTOM

 

I grabbed 327.23, doing some analysis of the patch for 320.18 now.

4 functions in total are patched, there is one reference to a very short piece of injected in a new PE section. I've located the appropriate patch locations in the latest 327.23 driver and are documenting them to make the patched driver now.

 

Interesting. You should post your results on techpowerup.

 

I've patched v327.23 in the same way that v320.18 was patched with adjustments of course for the minor differences. Patches check out in my disassembler. I just need to sign it with a certificate so it can be loaded in TESTSIGNING mode.

 

Nice! I was also going to say, the drivers there should work ok with the 750m if you put the appropriate entry into the list of supported cards in the nvidia .inf file for the drivers.

 

What is the exact name of the .inf file?

 

Are you guys aware of laptopvideo2go? They specialise in NVIDIA driver inf mods for laptops, etc. Maybe some of the experts over there would be of assistance in this foray?

LaptopVideo2Go: NVIDIA & Laptop News
LaptopVideo2Go hardware and driver community

 

Here's the patched driver for 327.23. I have not tested it so if it ends up breaking your Windows installation, not my fault. Full credits to anatolymik @ techPowerUp! forums for original patch.

DifferentSLI 327.23 x64

 

+rep

Anyone know where i could grab a GN35?

 

I've been seeing the GN35 on amazon. Dunno about Canada shipping though...

 

Yeah, i see one on amazon. Though at 199$ it's not looking very attractive, especially since i can grab one for around 140$ from a US retailer.

 

I wanna buy it from here and then have it shipped to Canada:

Buy Lenovo Y400 Removable Graphics GN35 Graphics/Video Accelerators 0C22230 today at PC Connection

Still haven't called Lenovo yet. I will ask them first if they still have some left in stock. I am not worried about the 170W brick yet, i just need to secure myself the card. If Ember's driver doesn't work, i'll just use it as a PhysX card for now, since i am currently using my Y410p for Solidworks.

 

Lenovo for sure doesn't have them (already tried that route a couple of weeks ago). I can use SLI just fine without the 170 watt adapter. I believe reports of needing it are a bit exaggerated. If you're doing some REALLY intense gaming with the GPUs and CPU fired up to 100% maybe it'll lack power, but I've been using it with 1100 mhz overclocks on both GPUs and haven't seen any issues...

 

Okay, i'll give PCConnection a Call, see if they can ship to Prince Edward Island (Canada). I'm also constantly checking Ebay, though i've only seen GN36 (Y5 series).

 

FOUND ONE! (Refurbished)

Shipped from Pinnacle Micro (4.5 star rating) and they do ship to Canada

Comes to about 150$ with shipping to my address, and i used a coupon for 10$ off

I will buy it tomorrow. Shippinh is 9-15 days. Wish me luck!

 

To reduce my TDP, i plan to perform something called a 4702'ing, which i will undervolt and underclock my 2.4ghz 47W 4700MQ to a 2.2ghz 37W 4702MQ using Intel XTU. Sure, i'll lose 5% CPU performance, but i will lower my TDP by 10W and cut down the heat a little. This should allow more wiggle room on the 120W adapter. Also, one thing about the Y410p is that the 14 inch display consumes less power than the Y510p's 15 inch display.

 

What is difference between GN35 and GN36? one is 650m, the other is 750m?

 

Nope. GN3x = 650M.

The GN35 is designed for Y400 (and Y410p) whereas the GN36 is for Y500 (and Y510p).

 

So lenovo has not sold 750m bay separately?

 

Only in China for Y410p, and for the Y510p you can buy models with the 750/755M but you can't buy the part alone.

 

Hi Ember,

Firstly, thank you for the patch - it does work.

Secondly, there's several threads going around GeForce, TechPowerUp(original), HardOCP and a few other forums where people were asking for updates on this mod, as Anatolymik had been MIA on the subject for quite some time.
With this in mind, I would be super happy and interested to take over managing the project for the users of these forums however could use a bit of advisement. Would you please spare me some time to walk me through a bit of the disassembly and binary differences in the nvlddmkm.sys?

I believe the hard part was already done -credit to Anatolymik-. It's now just about the upkeep and maintenance.

 

If you're good with scripting you could even perhaps make an automated buildbot that uploads to a FTP directory.

 

That's good to hear!

It would be awesome if an automated patcher could be made, I'll have to see if any generic search patterns could be made to make it happen.

I personally use IDA Pro, zynamics BinDiff plugin, a generic binary comparison program (e.g. Hex Workshop or UltraCompare), CFF Explorer, HIEW (used only for 64-bit assembler), and Visual Studio tools to sign the driver with a certificate so it could be loaded in TESTSIGNING mode (you can find out information on MSDN for this: Test-Signing a Driver File (Windows Drivers))

I compared Anatolymik's 320.18 patched driver to the original and found the patches were relatively simple other than a code redirection patched to an added PE section. Using zynamics BinDiff and UltraCompare revealed the patches as well. You can check in IDA by jumping to address and checking the code that was patched. For these patches, there is a string reference nearby that can be used as a marker to the general location of the patch, or you may need to check xrefs of the function to find a string reference. Once you have something to search for, you can just search that string in the updated driver to find the same location and note it down so you can patch it. I just used a hex editor to perform the basic patches. The driver is signed and what Anatolymik did was to add bytes between the signature and end of the file such that the signature started where the file ended, so I just added 0x0 padding using a hex editor as well. I used CFF Explorer to add a PE header section called ".addCode" (same as Anatolymik's, but I could have called it whatever, even .Ember if I wanted to as a "signature" of my work), and used HIEW to write the code that Anatolymik added to it (with adjustments for the stack offset, check in IDA). I used HIEW to also write the jmps to the section, and back to the main .text section. There might be enough bytes to pull off this patch without making a new section, but I didn't try at the time of making the patch and just chose to replicate exactly what Anatolymik did. After this you will just have to sign the driver with your signature, and package it up replacing the certificate and driver with the new patched ones.

If you don't know anything about reverse engineering software and usage of the tools I mentioned you will have a hard time doing this patch. Do not ask me where to acquire these tools I use - Google is your friend.

Otherwise, feel free to spread my patched drivers to those sites.

 

@Tester68

You just mentioned that you got SLI working using Ember's drivers.

Care to post about your SLI Y410p? I have yet to see one.

 

Will this work for the Y400. I believe they use the same bay as the old 650M, correct?

Otherwise could someone link me to where I can buy the 750m bay from China?

 

y400 and y410p are the same as far as the ultrabay. I bought my GT750M5 (compatible with y5xx out of the box and y4xx with mods) from ÏÖ»õ Y500 Y400 ÍØÕ¹ ÏÔ¿¨ GN36/35 Ultrabay Graphics GT750M4/5-ÌÔ±¦¶þÊÖ through a Taobao agent.

This driver patch is really just an attempt to get GN35 or GN36 (GT650M) cards working on laptops with GT750M's, so if you could find a GN35, you could in theory just slot it in and have SLI.

 

Will you please post some of your picture of your system? For example, GPU-Z and 3d mark11 score.
I am planning to get a gt650m ultrabay~

 

Will you please post some of your picture of your system? For example, GPU-Z and 3d mark11 score.
I am planning to get a gt650m ultrabay~