Introduction
This article is based on the previous voltmod article for the Radeon X800 Pro, X800 Pro VIVO, X800XT and X800XT PE AGP line and has been adapted to apply to the Radeon X800 Non-Pro, X800 XL and X850 PCI-Express line using PCB #A474.As always, the familar warning of "This will void the warranty" and "We take no responsibility of any kind should you damage your video card" applies before we start. Remember to take your time and don't over do it. You should seriously consider replacing the stock HSF if you plan to crank high on the overclock . Check out our GPU Heat Sink Fan Reviews here.
You should have at least tested your video card for a week under benchmarking and gaming before beginning the vmods to rule out issues prior to starting your vmods. Also, should you have any questions or information you wish to share, please post them here.
Chips
The chips that we will be working with are the same in both series, just in slightly different locations. With ATI's introduction of these cards they have new GPU cores as well.| Card Name | GPU Core |
|---|---|
| X800 | R423 |
| X800 XL | R430 |
| X850 | R480 |
The ATI's official X800 GPU temp specs remain the same for these cores:
The chips will be working with:
Thermal Parameter Value temperature Maximum recommended ASIC case (or center of die backside for flip chip) 105°C Absolute maximum rated junction temperature: TJmax 125°C Minimum ambient operating temperature 0°C
VGPU: Fairchild FAN5240MTC, Datasheet
VDD & VDDQ: Intersil ISL6522CB, Datasheet
The FAN5240MTC that we will be doing our VGPU voltmod on also has another use. Interesting info from Fairchilds product folder:
General description
The FAN5240 is a single output 2-Phase synchronous buck controller to power AMD's mobileCPU core. The FAN5240 includes a 5-bit digital-to-analog converter (DAC) that adjusts the core PWM output voltage from 0.925VDC to 2.0VDC, which may be changed during operation. Special measures are taken to allow the output to transition with controlled slew rate to comply with AMD's Power Now™ technology. The FAN5240 includes a precision reference, and a proprietary architecture with integrated compensation providing excellent static and dynamic core voltage regulation. The regulator includes special circuitry which balances the 2 phase currents for maximum efficiency.
Max. safe voltages
| VGPU | |
|---|---|
| Stock: | 1.31V - 1.41V |
| Air cooling: | ~1.45V |
| Water cooling: | ~1.7V |
| Phase change: | ~1.85V |
| VDD | |
|---|---|
| Stock: | 1.95V - 2.05V |
| Active + Passive cooling: | 2.45V |
| VDDQ | |
|---|---|
| Stock: | 2.04V - 2.10V |
Overview
Overview- click on pic to enlarge
Above image gives us our vmod locations and points of reference. The blue Sapphire PCB #A474
has the same layout as the red ATI PCB, so it will work on all those models, no matter which manufacturer.
To the bottom right our arrow color code for the chips and measurement points, with the yellow arrow for our IGPU vmod.
As in the last article we'll start with the Pencil Vmod, along with the VID Vmod. The VID Vmod is something new to some of you and is the voltage identification code (VID) that sets the resistor divider for different output voltages. Which has been used by ATI since the 9800 PCB and by using 5 pins labeled VID0 to VID4 on the FAN5240 pins 7-11 are used to set the default voltage. With the VID table provided from the datasheet we can change the default voltage setting.
Tools and Supplies
- Digital Multimeter (a must have to complete mod safely)
- Magnifying Glass
- Electrical Tape (get the color that matches your PCB)
- 2b Pencil (works the best, found one at Staples in Drafting Department)
- Conductive Pen
Starting Prep Work
Before we get down to work, let's run through the multimeter to make sure we are on the same page.You will be using two different settings. One to check the voltage before and after we make our changes. The second to check the resistance in Ohms of the resistors we're using our 2b pencil on, to safely lower their resistance to raise the voltage.
To check the voltage for the VCore and VMem starting measurements, set the multimeter to DCV 20V and to check Ohm resistance you'll set the meter to Ohms 2k or 20k depending on the resistor we're working with.
Measure GPU Voltage
Begin with writing down our starting voltages using the above pic, labeled Overview. Starting with locating the green arrow pointing to the capacitor close to the middle of the board labeled C60.Now with the system running and the side cover off, visually inspect the area to first locate the capacitor and making sure there isn't anything in the way. Set your meter to DCV 20 V before placing the black lead of your meter on the screw holding in the video card, this is ground. Important when touching card with a meter lead that you don't accidently ground something out. Carefully place the red lead on the top side of capacitor C60 (you're upside down from the pic facing the card). Your meter should be reading around 1.40 V, cards vary from manufacturer to manufacturer. Write that VCore number down for future reference. There is not a measure point for the IGPU Vmod that I'm aware of at this time.
Measure Memory Voltage
Lets move to the VDD (VMem) & VDDQ measure points. In our Overview pic above, locate the green arrows pointing to our measure points, over to the left of the card labeled C1928 for the VDD and C1807 for the VDDQ. For a closer view click on the Overview pic to enlarge. With the same steps we used in the previous measure point. Place the black lead on ground carefully placing the red lead on the top side of C1928 (you're upsidedown from the pic facing the card). Your meter should be reading around 2.00 V. Record this as your default VDD voltage.Now we are taking the last default voltage. Find the measure point in our Overview pic above, locate the green arrow pointing to capacitor C1807 for the VDDQ. Once more with the same steps as before place the black lead on ground carefully placing the red lead on the bottom side of C1807 (you're upside down from the pic facing the card). Your meter should be reading around 2.08 V. Write your VDDQ number down.
Now these numbers can be important in the Pencil Vmod and the VR Vmod. Before starting up the card, we can check the resistance to have an idea of what the starting voltage will be. Better safe than sorry and everyone should take care whenever vmodding, for the hardware and yourself.
Pencil Vmods & VID Vmods
We are seeing so many different variants of the ATI PCB from the OEM manufactures in regards to the layout of components, to the lack there of. For some this will be bad news, given the fact that there is no longer a SMR at R1597 on most PCI-E cards. This renders the pencil Vmod for the VCore unable to lower resistance to raise voltage enough to make a difference by just using the two solder pads to which the graphite will not stick. The reason for the not having the resistor can be best explained by ViperJohn.by: ViperJohn
ATI didn't have to populate and create the voltage divider on the x850 PWA because they changed the VID jumper programming to increase 5240's programmed regulation setpoint from the gitgo.
Doing that they didn't have to trick the 5240 into regulating at a higher voltage by reducing the feedback voltage with a divider.
Which means we now have to use the VID vmod to change the VCore, but this is not adjustable. This however does not affect the use of a variable resistor as before and does not mean you still can not try the pencil on the VCore. Thanks to Kramda for reminding us of the Fan5240 VID settings.
With your card out of the system and your work area static free. Basically what we are trying to do is use our 2b pencil to reduce resistance on the selected resistor. You'll need to measure the resistance in Ohms first, by placing the black lead on one side and the red lead on the other side of the resistor, write it down it's our starting Ohm reading. Then gently run your pencil along the side of the resistor from one end to the other. Do a couple swipes then check again with the meter. Using the number you've written down subtract the new reading. For example, if your starting Ohm reading is .418k and your new reading is .400k obviously it's a 18k drop in resistance. If you go by the rule of 15k Ohms equals roughly .04V to .06V. Add the .04V - .06 V to the reading that you saved for future reference, for example the VCore reading of 1.39V your voltage should now be around 1.43V - 1.45V. A 10k variable resistor will give you around .04 Volts so again that's around 15k Ohms you need to reduce your resistor.
Keep in mind that if you want your card to last awhile don't get greedy.
VCore & IGPU Vmods
VCore & IGPU
Using the image above as our guide locate where the resistor R1597 used to be under the pencil labeled VGPU for those of you who still wish to try the Pencil Vmod. This is the two solder pads you will use the 2b pencil on, following the steps we went through above, but without a resistor, you'll try to use the space between or on either side of the pads to build a bridge.
Set your multimeter to 20k Ohms. A VCore voltage of 1.45V to 1.50V should work well. After you have reduced the resistance, place the card back in and power up. Check your VCore voltage again to verify the amount of voltage you're now running at. Test the card for artifacts and lockups. If all is well, use a piece of electrical tape and cover your work area. Review the max voltages suggested for cooling needs.
Now in most cases if not all, you'll need to do the VID Vmod to change VCore
The IGPU or Over Current Protection vmod is only needed, if you are applying a high VCore vmod. The higher the voltage your GPU runs at, the more power it consumes, the higher its current draw.
The VCore regulator chip has a built-in overcurrent protection feature which shuts the card down, if a certain amount of current draw is exceeded. This mod raises that limit.
In the above pic use a 20k Ohm reduction in resistance for OCP vmod, which is applied to resistor R1596. Since there isn't a measure point, remove the card and set your meter to 200k. Check the resistance on the resistor R1596 which should be around 40k Ohms. Lower the resistance by 20k Ohms.
VID Vmods
VID Vmod
VID Table
The VID Vmod requires a conductive pen or jumper to work. Looking at the image above, labeled VID Vmod, we can ascertain our default factory voltage by the placement of the SMR resistors by using the VID table below it. The picture shows a card with VID code 01101, which is 1.35V. By looking at the VID Vmod pic we can see, that there are SMD resistors at VID1, VID4 following the lines from pins 10 & 7 and by using the VID Table we use a zero(0) to show a resistor is present, with a 1 meaning no resistor present. So using 1.35V as an example to up the voltage using the VID setting we would use the VID table to determine a higher voltage with the same two SMR in place like the 1.55V setting to which we just connect the solder pads at VID2 with our conductive pen. Which would give a VID code of 01001. Unfortunately this limits our choices and for those with a 1.40V default voltage means the next available VID setting would be 1.60V without removing a SMR. Of course all is not lost if you are using a Water Block for cooling.
VDD & VDDQ Vmods
VDD Vmod
In above image locate the VDD labeled pencil above the resistor R311. This is the resistor you will use the 2b pencil on, following the steps we went through above. Set your multimeter to 20k Ohms. A 20k variable resistor which will give you around .08V Volts, you'll need to reduce the resistance around 30k Ohms. A VMem voltage of 2.08V to 2.12V will work fine. After you reduce the resistance, place the card back in and power up. Check your VMem voltage to verify the amount of voltage you are running your memory at. As we did in the VCore vmod, test the card for artifacts and lockups. Use the tape to keep the graphite in place. Review the max. voltages suggested for cooling needs.
VDDQ Vmod
This one will be a little tough given the resistor is in a tight spot. Again in the above pic locate the pencil labeled VDDQ above resistor R256, this is the one you'll need to pencil mod to increase VDDQ voltage. Set your meter to 2k Ohms this time. With the info of a 20k variable resistor giving .08 Volts we'll need to reduce resistance around 30 Ohms. A VDDQ voltage of 2.16V to 2.18V will help with both VCore and VMem. Check the voltage to verify the amount of voltage you're running at. Test for artifacts and lockups. Use the tape to keep the graphite in place. Review the max. voltages suggested for cooling needs.
Using Variable Resistors
Understanding the same warnings as posted previously in the begining of the article. You should read the "Introduction" and "Starting Prep Work" sections.There are many different ways you can do the Variable Resistor (VR) vmods. Each one is a personal preference on how you want you card to look and how much time you wish to invest in the vmod. From the color of the VR to where, how to place it and if to use wires or even adding a switch to turn off the vmod. Of course I have to mention that you need good soldering skills to perform the vmods using a VR. So take a moment to view some of our members VR vmods to get ideas and to post your pics at techPowerUp! here. Great work guys and thanks for taking the time to post the pics.
Overview- click on pic to enlarge
The above pic gives us our vmod locations and points of reference. The blue Sapphire PCB #A474
has the same layout as the red ATI PCB, so it will work on all those models no matter which manufacturer.To the bottom right our arrow color code for the chips and measurement points, with the yellow arrow for our IGPU vmod.
Tools and Supplies
To do these mods you should aready have soldering skills and should be using a low wattage iron.- Digital Multimeter (have to have one)
- Magnifying glass
- Glue Gun (to set VR in place)
- Variable Resistors: 1x 10k Ohm, 1x 250k Ohm, 2x 20k Ohm
Next, read the "Starting Prep Work" section to get your default voltage. This can be important to get an idea of where your voltage will be when you crank up the card. You can still use the same table as the pencil mod. What I mean by that, is if the default Ohm reading of the VGPU is at 420 and you add the 10k VR, then given that a 10k VR will give you around .04V which in turn equals 15 Ohms then after adding the VR your new Ohm reading should be around 405 Ohms.
VR VGPU & IGPU
VR VGPU & IGPU
Locate the two solder pads in the above pic, where you will use the 10k VR for the VCore vmod. Set the VR to 10k or as close to 10k as it will go using your mulitimeter. Check the resistance to compare after you solder the VR. You can either solder the VR to the resistor directly or you can use wires. After soldering the VR on, check the resistance. Remember a 10k VR should give you around 15k Ohms Verify the voltage and test your card for artifacts and lockups. Review the max. voltages suggested for cooling needs.
Locate resistor R1596 in the above pic and set your VR to 250k. Check the resistance on the resistor to compare after you solder the VR on. Again, after soldering the VR on check the resistance. Like with the pencil mod you want to drop the resistance around 20k Ohms. Remember this vmod does not increase your overclock, but increases the max. you can set the VGPU voltage before the card will shut off.
VR VDD & VDDQ Vmods
VR VDD
Using the above image we will solder a 20k VR to the pins 5 & 7 of the VDD chip ISL6522CB.
Set the resistor to 20k or as high as it will go and check the resistance before, then after you solder the VR. Verify the voltage and test your card for artifacts and lockups. Generally speaking, it helps to do the VDDQ along with the VDD vmod, in other words if you do the VDD you should plan to do the VDDQ as well. Review the max. voltages suggested for cooling needs.
VR VDDQ
Same as the last vmod, use the above pic and solder a 20k VR to the pins 5 & 7 of the VDDQ chip ISL6522CB. Set the resistor to 20k or as high as it will go and check the resistance before, then after you solder the VR. Verify the voltage and test your card for artifacts and lockups. Review the max. voltages suggested for cooling needs.
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