Article extracted from http://vr-zone.com/articles/amd-radeon-hd-6870-memory-voltage-modification–with-a-pencil/10160.html
We reviewed the AMD Radeon™ HD 6870 just a week ago, and found that it had a pretty decent overclocking headroom. One of our samples even managed a good1GHz on its Graphics Processing Unit (GPU).
At this point, it started looking like the graphics accelerator would very much like some extra memory bandwidth. This seemed impossible if we were unable to increase the memory clock speed.
Knowing that you readers wouldn’t take “no” for an answer, we pondered the issue over a meal at the local IKEA store.
Then we pilfered a pencil (OK, we actually took more than one). Like all great napkin-ideas, this modification costs next to nothing.
Step One: Identify your Memory Voltage Measurement Point
The one is easy, just jam the black probe of your Digital Multimeter (DMM) into one of the grounded hollows of the PCIe power inlet.
Touch the red probe onto the solder joint highlighted in the picture above. You should get an approximately 1.6V reading when the graphics accelerator is in “3D.” Our sample reads 1599mV.
Step Two: Take it Out!
The next part involves removing the Radeon HD 6870 from your PC system, and ripping off the default thermal solution. This will allow you to gain access to the memory Voltage Regulation Module (VRM), as well as the critical feedback loop.
What? You are still using the default thermal solution?
Maybe you really should consider reading the Homemakers magazine instead.
Step Three: Zoom In On What Matters
With the default thermal solution out of the way, you should be able to find (on the same face as the GPU package) the area depicted below:
Step Four: High School Art Class
With your favourite pencil (a 2B grade one works alright), shade across the highlighted 0402 resistor. You may wish to check the resistor value just before you engage in this absolutely pleasurable act – it measure approximately 5kOhms.
We shaded across our resistor (with our lethally-sharpened IKEA pencil) until the effective resistance dropped to approximately 4.4kOhm, and with that, memory voltage rose to 1819mV. A darker shade will naturally increase your memory voltage even further.
To prevent graphite shavings from irritating neighboring resistors, you can mask off the surrounding area with your favourite insulating tape.
Step Five: Put it Back In!
It is now time to slap back whatever thermal solution you took off earlier (or upgrade to a superior one), and put the modified Radeon HD 6870 back into your PC system. Keep your DMM probe on the memory voltage measurement point, while you hold your breath and power up your system.
In the meantime, hold your breath, cross your fingers, and pray hard that your latest acquisition does not burst into a ball of flames.
Once the graphics accelerator has initiated, make sure that you have your desired memory voltage. If it appears too high for your liking, power “off” the system immediately and work on increasing the effective resistance of the the resistor by brushing off excess graphite.
Drum Roll…
We managed to gain an extra 40MHz on the graphics memory with the aforementioned memory voltage, and a corresponding improvement in graphics performance.
This puts us at 1180MHz on the memory frequency, 20MHz short of the 1.2GHz ballpark, but that shall be something you readers can try out – for next to zero cost!
When you finally get there (or beyond), don’t forget to shout out loud on our Forums.
As usual, VR-Zone.com shall not be responsible for any damages arising from the users of this tried-and-tested guide. If it befuddles you, forward it to someone else and forget about it.
