SLI'ing Y410P GT750M with GT755M Natively! No driver mods.

Summary:
I own an early version August 2013 y410p with 1.07 BIOS and single GT750M. I wanted a 750m Ultrabay for SLI, but Lenovo never delivered. So, I bought a GT755M5 ultrabay when it was on sale for $99 dollars (instead of the now $275 dollar price), and made it work without ANY BIOS modifications.

GT755M5 Ultrabay Card from Lenovo - For Y510P

The laptop is natively supporting SLI without any driver or BIOS modifications. Here's how I did it.

Requirements:
-GPUs need the same device IDs 10DE 0FE4 (subsystem ID does not seem to matter, but mine is 3800 17AA whereas I THINK the y510p's are 3801 17AA)
-vBIOS should be the GT750M vBIOS, mostly just for clock speeds. The card pulls device ID off of the hardware straps
-It needs to actually fit in the laptop

The First Step....
I tried just flashing the 750M vBIOS onto the 755M to see if I could get past the BIOS whitelist. I used a Raspberry PI to SPI flash the Lenovo provided 750m vBIOS for Windows 8.1. However, that did not work. Here's some pics for fun:

SPI Flashing 750M vBIOS onto a 755M card with a Raspberry PI

The Second Step....
User @EmberV was extremely helpful in this part. I posted PCB pictures of the GT755M Ultrabay, and he pointed out that although the GT750M and GT755M were the same chip, same RAM, even the same PCB... there was ONE resistor that was configured differently.

GT755M5 Ultrabay PCB Pictures

Pictured below are the hardware straps.

GT755M Left, GT750M Right



GT755M Resistor Pattern (Left)
10110010
01001101

GT750M Resistor Pattern (Right)
10111010
01000101

First thought was that they were just 0 ohm resistors configuring the Device ID, however they are actually resistors, in increments of 5k Ohms, between 5K and 45K which set the Device ID.

More on how Nvidia does hardware straps here:

Hacking NVidia Cards into their Professional Counterparts

One of my buddies has a y510p GT750M SLI laptop and he was kind enough to allow me to take his Ultrabay apart and poke it with a DMM. This is what I found, with the upper left most resistor being pad 1 and the bottom right most resistor being pad 16.


GT755M picture above with pads labeled


Respective resistor layouts for 755M (Left) and 750M (Right)

Previously, the y410p would tell you that the Ultrabay is unsuitable for the laptop and tell you to remove it so you couldn't even boot into Windows. Making these changes allowed my y410p to get past the BIOS whitelist and into Windows. Simply re-flashing the chip again with the GT750M vBIOS from Lenovo (the one released for the Windows 8.1 issue) got it working properly and the next time I booted my machine I was greeted with this:



Now I'm pushing >200FPS in CS:GO, BF4 on Ultra, Tomb Raider on All high (except stupid TRESSFX)... It's great, just now I need to undervolt the CPU to prevent throttling .


Side note:
Modifying the hardware straps requires you to solder SMD 0402 size resistors, which is not an easy task if you don't have the right equipment. To put it in perspective, here is the 30K resistor I desoldered from the GT755M card.



The ridges in the picture are my fingerprint! Optics and a high quality soldering iron are necessary to do this soldering job.

You can follow my incremental progress on this thread starting from page 8, although it veers off topic a bit:
Y410p [SLI] Purchase - Page 8

tl;dr:
1) modify hardware straps
2) reflash
3) happiness

If you have any questions about how I did this please let me know and I'll try to answer as best as I can.


Special thanks to @EmberV for helping me through this mess. Definitely could not have done it without him.

 

Definitely not for the faint of heart LOL.

 

Since the 755M isn't $99 anymore I'd just recommend the actual 750M ultrabay haha. That being said, nice work.

 

I would ask for a video, but it seems redundant to ask you to do this all over again. I'm still confused on the technical parts, and have no idea what you're talking about to be honest

P.S. Also, would this Y510P 755m Ultrabay work? Y510p Removable Graphics GT755M5 | Lenovo | (US)

 

That's the exact utrabay he used. It had to be physically altered to work with the onboard 750M (since it's a 755M) and since it's a y510p ultrabay (the y410p's ultrabay has different dimensions). I'd just go with the 750M ultrabay now however, since the 755M isn't on sale any longer.

 

@LordTempus Honestly, I don't think a video would help much. Looking over the PCB pictures, understanding what is going on with the hardware straps, and a decent set of tools is all you need to do this modification. If you want anything specifically cleared up let me know. There are only three resistors pads that need to be changed to fully convert the GT755M into a GT750M.

GT755M5 Just went on sale for $99 dollars again.

 

First off, congratulations on achieving this. I have been following every step of your work from the other thread and I understand the whole process called for some real patience and hard work.

Where did you buy the 2 resistors from and what kind of a soldering iron are we talking about? I have some experience with the process (very much an amateur though). Would an iron like the one in the link along with a magnifying desk lamp be good enough?

Weller SP40NKUS 40 Watt LED Soldering Iron Kit, Red/Black - - Amazon.com

Amazon.com: Carson DeskBrite 200 LED Illuminated 2X Magnifier & Desk Lamp (LM-20): Sports & Outdoors

I was checking out some videos on how to remove SMD resistors - I understand it's not an easy task sustaining heat in both ends of the resistor. Is it all skill or do you need special irons to remove them?

 

But, you can't get the 750m ultrabay anymore... haha. They only sell the 755m... haha. And good luck trying to find the 750m ultrabay anywhere... haha.,

Okay, guys... I spoke with the only friend I know who might have had the equipment and skill to do this and, it turns out he doesn't.

 

@GovindB Thanks

I got my resistors from Mouser.com, although there are many retailers out there you could buy the resistors from(digikey, westfloridacomponents, ebay if you wanted to, etc...). The resistors are size SMD (Surface Mount Device) 0402 (Indicates the size). I used a "solder sucker" to remove the hot solder from each end, then was able to wiggle the resistors off with a pair of sharp tweezers one side at a time. It takes less than a minute or two to remove each resistor. Just be conscious of how much heat you are putting into the board (give it a moment to cool if you're on it for more than 10-15 seconds). Replacing the resistors is as easy as smoothing the solder surface with the iron, and then just applying a TINY amount of solder to each end after the resistor is seated. I of course checked the impedance with a multimeter before/after on each pad and made sure the solder joints were strong. Just a note, I measured the resistance of all of the pads, even the ones that didn't have resistors seated in them to make sure there were no shorts. The open pads are usually >60k-ish ohms anyways.

I went out an bought a nice Hakko FX888D soldering station because my access to the labs on campus got revoked (I graduated). Figured that I needed to replace my crappy 15W RadioShack wand anyways. What you need is a soldering iron with a very sharp conical tip, and it looks like the Weller comes with one. Temperature control is also nice, but NOT necessary since resistors aren't very temperature sensitive anyways. Desoldering wick is nice to get the old factory solder off, and Flux helps greatly when trying to reflow the solder.

Assuming you have a lamp + electricity, you should be good on light. That magnifier you linked is a bit on the pricey side though. I used a Helping Hands which is more or less a movable magnifying glass with clippy hands. And it's cheap too which is nice. Not sure what the magnification is, but it's enough to do the job. If you wanna stretch, you could probably get away with using a smartphone with a >8MP camera, macro focusing, and digital zoom. But that would be more of a hassle than it's worth.

Very fine solder is a good idea too.

Oh and get tweezers. Really pointy ones.

Also buy extra resistors (at least 3), they are like 8 cents each, and it's better to be safe than sorry when one falls into the void or your hand slips! These things are minuscule.

If you're new to soldering, I would suggest just finding some old computer parts/video cards/motherboards and practice removing/replacing components on it first. It can't hurt to practice.



PS: There's a bunch of stuff hyperlinked in the paragraphs above, but they are hard to see and faintly colored. Maybe because I'm color blind

I honestly wouldn't mind doing it for you, but the liability is where I get reluctant on the idea :| I would hate to mess up somebody else's $100 dollar GPU! Lenovo is so ridiculous for not releasing cheap 750M Ultrabays... WE JUST WANT TO PLAY VIDEO GAMES!!!

 

I understand. Once you figured out how to do it, it seemed pretty straightforward for you, though, yeah? I've got a y510p and they simply aren't selling the GT750m for those anymore... only the GT755m. So, if I want an ultrabay, the only option seems to be this.

 

I purchased the GT755M5 with the expectation that it WASN'T going to work so I had no problem with poking/prodding my own GPU. If I lost $100 bucks, then that's what it was... But if it did work then woohoo!!

It was just for fun and I thought it would be a cool project to do on the side. Luckily @EmberV already did half of the work for me

 

I'm of the same mind, actually, in terms of having the GPU tinkered with... just without the technical know-how. I contacted a friend of mine who I thought might've been able to do it, but he feels it's over his head.

 

Appreciate the comment brother. As you mentioned in a previous post, it seems like a cool project to do on the side; and even if I fail, its a $100+40 loss (accounting for the tools) which isn't so bad when you consider what could be gained from a job well done. Thanks for providing a detailed guide and links to the products. I shall be getting the tools pretty soon and I'll update the thread about my progress. Even if I end up not doing it for some reason, it's a great feeling knowing there is at least one way to seriously ramp up the 410p's performance.

 

For anyone that's interested (I probably should have posted this earlier)
-80mV undervolt on 4700MQ
Turbo Disabled (2.4GHz only)

3D Mark 11 Basic
Single 750M:
3D Mark Score: 2932
Graphics Score: 2760
Physics Score: 5492
Combined Score: 2383


Dual 750M:
3D Mark Score: 5066
Graphics Score: 5363
Physics Score: 5421
Combined Score: 3348

Temperatures never passed 83C on 3DMark 11

Firestrike(1080p):
Single 750M:
3D Mark Score: 1980
Graphics Score: 2100
Physics Score: 6036
Combined Score: 813
NVIDIA GeForce GT 750M video card benchmark result - Intel Core i7-4700MQ,LENOVO 20216

Dual 750M:
3D Mark Score: 3058
Graphics Score: 3682
Physics Score: 6047
Combined Score: 1016
NVIDIA GeForce GT 750M video card benchmark result - Intel Core i7-4700MQ,LENOVO 20216

A little under 2x scaling graphics performance for 3Dmark tests.

 

Very nice. I may pick up that 755m card soon.

 

Why are your physics scores so low? Does undervolting really take away that much performance, or is it simply Lenovo throttling kicking in?

Anyways here are by best Fire Strike scores. I ran these tests back in November, with a 120V adapter so my overclocks weren't as high as they could have been.

NVIDIA GeForce GT 650M video card benchmark result - Intel Core i7-3630QM Processor,LENOVO INVALID

 

He disabled Turbo Boost so the 4700MQ only went up to 2.4 GHz. But still, the Physics Scores are on the low side even accounting for that.

 

*shrug* idk why. Just reset all settings to default and let it boost and only hit about 6300 on physics.

Maybe all those long hours of 90C+ gaming are taking a toll on my die. Or maybe Windows 8.1/SSD cache/something.

Undervolting shouldn't give any performance hit at all. No clue.

 

Are you using ThrottleStop?

 

I was using Intel XTU and probably jonx'ed up some setting ¯\_(ツ _/¯

 

Arg! Dude, pissed! Lenovo cancelled my order for my GT755m Ultrabay, and the item is listed as no longer avialble on Lenovo.com.

Edit: Called (and online chatted) with Lenovo. The GT755M5 is end of life and will not be restocked. Apparently It wasn't even supposed to listed on Lenovo.com for sale.

The GT750M4 is vaporware and never existed, the GT750M5 never worked and hasn't been available for sale for months, and now that there is a work around to get working SLI on a GT750M Y410p, the GT755M5 goes EOL. Incredible.

 

Classic Lenovo :/

 

And exactly why I will never be buying another Lenovo product.

 

Can't agree more. I wrote a *very* well worded email to the Lenovo web sales team (CC'ed CMO David Roman) expressing my disappointment with the Y410P Ultrabay. I received a canned form letter response.

 

Wow, I guess I got lucky when I purchased my y400 then. I only recently purchased a GN35, to replace the wonky GN36 I was using before. Why Lenovo still has all the y400 ultrabay accessories in stock I don't know, but I'm grateful

 

First off, bcunje, excellent work.
I would like to try the reverse of what you have done here, and turn a 750m into a 755m.
I contacted you earlier through Steam, but I have come across several questions about your process that are too complicated to ask in that way.

First off, in your table of resistor values that set the device ID, I understand why you changed resistor numbers 1 and 5, but why you simply removed resistor 13 confuses me. Here is your table for reference:


Why did you remove it, instead of changing it to an 80K ?


Secondly, how did you flash the vbios onto the card? Did you use the Raspberry Pi again? Or did you use this method: [GUIDE] NVIDIA VBIOS flashing ?

And my last question: Where did you get the correct vbios from?

 

@Archaox , sorry I guess I didn't really explain the complete omission of resistors. Any resistor value on that table that isn't an increment of 5K Ohms and between 5K-45K is NOT a resistor. I measured the resistance of the open pads on the PCB just to show that they are >80K or so, and have no real importance (also to make sure it's not shorted). There are 2 rows and 8 columns, so to say, of resistors on the PCB. Each column only needs one resistor, so on all 16 pads only 8 of them will be populated. This is how the card itself reads the resistors and determines the device ID.

Nvidia uses 5K, 10K, 15K, ...... 45K resistors to strap the device ID.

Once you change the resistors, your laptop will allow you to boot into Windows, so you can flash through software using nvflash.exe. The card will show up in Device Manager but will not be working properly since it has the wrong vBIOS on it. There are tons of guides on how to use nvflash.exe, but my guess is you will be using something like "nvflash.exe -4 -5 -6 -i 1 750rom.rom"

No need to use a Raspberry Pi/external flasher, unless you don't have a functioning y410p .

You can download the 750m rom files directly from Lenovo's website on the support page. It's actually their fix for the Windows 8.1 SLI issue, which is the rom you will want.

I cannot confirm if going from 750m -> 755m will work since it's never been done... but 755m -> 750m has been confirmed working twice.

 

Thank you for your clarifications, bcunje!

As it turns out I don't need to turn a 750m -> 755m because lenovo just put the 755m cards back up for sale! Yay! 99$ right now if you are interested, but the sales rep said that they only had so many and would sell out very quickly. Note: they are for the y510p, so do know that some plastic needs to be removed here and there.

Just so you know, I very much appreciate the time you put into that reply- I know time is hard to come by nowadays. I would say that I'm sad I didn't get to try out a 750m -> 755m conversion... but I'm actually happy that it turned out easier than that.

 

I'm looking to sell my Y410P along with its Ultrabay peripherals.

-Y410P (4700MQ/750M/1TB + 128GB NGFF/8GB) w/ custom 120mm X 2 notebook cooler + repasted
-"GT750M4" (custom 755M converted to 750M with a 14" bezel, can be used to SLI a Y410P with single 750M w/o any bios modification) + repasted
-GN35 GT650M5 (15" bezel) + repasted
-240W Dell/Alienware PSU with adapter for Lenovo
-4 Port USB 3.0 Hub

The "GT750M4" is a one-of-a-kind Ultrabay GPU accessory which isn't sold by Lenovo. PM me if you are interested.

I know these Ultrabay cards are in short supply and cannot even be purchased from Lenovo anymore, so PM if you are interested.

 

Hi, bcunje..

I success with the hardware mod.. and i can get the windows to detect the second graphic..

but i'm stuck with the vbios..

already tried nvflash -i 1 -4 -5 -6 9D3D.rom

but the command prompt closed after
"WARNING: debug port will be disabled during EEPROM access."

any idea how to flash the bios?
thanks

 

@adhyatma use a hardware flasher. bcunje used a Raspberry Pi and flashrom to flash the vbios from Lenovo's support page.

 

@ember
Thanks for the reply

But i think bcunje said that no need to use raspberry pi/external flasher
Just flash from windows..

But if u said it needs external flasher it worth to try

Do you know how to do it?
Because from what i read u are bcunje friend who acompany him to this success right?

Please help me..

I used windows or DOS type of nvflash
But the result is same

After it says:
"EEPROM ID (20,00FF) : Unknown"
"Error: Supported EEPROM not found"

Nothing happend..

or do you have bcunje contact?
email or something else..

 

@adhyatma please try and pull the exact EEPROM model number and make sure it is compatible with NVFLASH. It does not make sense that you can't flash your card, even from Windows. Try and just run the Lenovo provided vBIOS update and see what errors it gives you. At the very least you should get a card mismatch (but compatible EEPROM!).

I initially flashed the card with a Raspberry Pi (experimenting), but ultimately ended up re-flashing it from Windows. Both should work.

Another thing you can try is to make sure the EEPROM on the card isn't in protect mode. The GT650M I was messing with wouldn't let you flash it unless you sent the protect disable command first. You can send the protect disable command from NVFLASH, I don't remember exactly what command it is though. I'm sure you can find it in the NVFLASH help menu.

 

@bcunje
if i used the provided NVFLASH from lenovo..
the nvflash closed it self after i click it..

if i added some command
nvflash -i 1 -5 -6 -r -j 9D3D.rom

i got:
"EEPROM ID (20,00FF) : Unknown"
"Error: Supported EEPROM not found"
and it closed ifself

still stuck..

the write protect off command is -r

do you flash it on Windows 8.1?

 

@adhyatma Yes, I flashed on both Windows 8/8.1. Something else must be wrong with your GPU then or your flash command isn't formatted properly. Regardless of if you did the resistor mod or not, you should be able to force flash the EEPROM with nvflash if it's a supported SPI chip.

1) Check the GPU using GPU-z. Make sure it actually exists...
2) Try running the -list command from nvflash, and make sure it sees two cards.
3) Check BOTH gpus that come up in the list. GPU #0 (i think) will not work because it's the built in gpu. You shouldn't be able to flash the built in one, so don't worry.
4) Make sure you're running the latest version of nvflash.
5) It should work...
6) Open your ultrabay and read off the actual model number on the flash chip. Make sure that chip is supported by nvflash.
7) Raspberry Pi/SPI Flasher + flashrom

Sorry I can't be of more help.

 

@bcunje
hi can you send me a copy of the stock bios verion 1.07 ? thanks!

 

@bcunje

please help i want to use the gt 750m i bought. because it shows as an unauthorized vga. so i want to the the resistor mod. and copy the resistor layout you posted.

may i know what type of smd 0402 resistor did you use, i looked through mouser but there are different types of resistors, thin film, thick film, metal foil, metal film, etc. and the case code should it be in "in" or "mm".

 

@bcunje
Sorry to bump this thread from the past, but I'm looking to do the same modification to use the card for my Y510p. I'm looking over the resistors from Mouser- do the resistance values have to be spot on with the values given in the spreadsheet? How much margin of error is acceptable for the hardware straps to be recognized with modifications? The available resistance options for 35k are anywhere from 34.8k to 35.2k

 

Thank you for your guide. I have a motherboard with GT755M and the Ultrabay GPU is GT750M. Is it possible to mod the Ultrabay GPU to GT755M?

 

Hello there!

I have a y410p in which I want to use a gt750M5 ultrabay to build a SLI.
Last night I removed the front panel of the gt750M5 to let it fit in the y410p ultrabay. The first time it seems it worked. I was playing around over the nvidia control panel, the second card was detected correctly but after a while the laptop just rebooted without any advice. After that I got the "Unauthorized slave vga card is plugged in. power off and remove it" message.

I am trying to build the SLI using the 3.08 BIOS. I read somewhere that older BIOS will accept this external GPU but I can not find any source in which I can download older versions of the BIOS for this laptop. Can anyone share the stock BIOS version for this laptop please?

 

Is there anywhere in USA to get the Y410P Nvidia Ultrabay Video Graphics Card GT750M
On eBay, I only see them from China and I don't feel iike waiting over a month to get it from there.
Plus, if it came from China and doesn't work, it is a nightmare to send it back...