XFX 7970 VRM Temp FIX!

Hey all,

Registered just so I could share my fix with everyone else still running most versions of
the infamous XFX 7970's (DD, BE, etc.)

Common issues are artifacts, throttling and glitching, mostly caused by high VRM temps.

After using them for a year and trying to ignore the issues, I decided to take a closer look
at the VRM area... this is what I discovered;



Looking at the bottom of the heatsink unit, you can see the black metal finned strip with
the thermal tape on it that cools the VRM's. Directly underneath it (on top of it when it's
right side up) is the aluminum heatsink for the core with the two fans mounted on it (not
shown). Upon further inspection, you will notice that the core heatsink is flattened on this
side, not finned for air to pass through. BLOCKING any and all air coming from the fan
to the VRM heatsink. I'm not entirely sure why XFX thought this was a good idea, but it
is the cause of the majority of issues with this card.

Here's what I did:



Looking at the VRM side of the heatsink with all the fans and wires off and out of the
way, you'll notice where the copper base ends. This is where you're going to cut off the
end of the heatsink, exposing the entire VRM area and black heatsink for the VRM's.



I used a hacksaw and squeeze held the heatsink so they didn't bend or warp while \
slowly cutting through. It takes about 2 mins to do taking your time. I imagine you can
also use a Dremel if you're so inclined. This is what it looks like when it's done;



Make sure to completely clean up any loose metal bits, shavings or dust before
repasting and reassembling and enjoy your new fully functional card! My VRM's were
around 105 Celsius before doing this, now sitting at par with core temps around 78
Celsius with fan speed at 40% and no more glitching, artifacting or crossfire issues.

You know if this works for their 280x cards? They have a similar problem but the design looks so different.

Only way to know for sure is to check it out for yourself... if it's a vapor cooled heatsink then it would be harder to remove the fins as there's tubes attached along the length of it. It would more than likely be possible still, just harder to make space for air to travel through without it damaging the tubes (DON'T cut them if you have them, btw), or potentially reducing the cooling capacity for the core.

I dont get it because , cutting it cant get the temps this low , the reason they have long fins are to increase the surface area so the heat dissipation with be high , but if you cut it its going to become high.
Also because one side of the vram sink is connected with main heatsink the heat will conduct through the fins and dissipate.
The reason may be you got it fixed is:
1. the stock thermal pads were not in good contact with the heatsink
2. those thermal pads may be mis aligned.

OR you could open those closed fins using a small flat screw driver , so it wont have a impact on the core temps and will reduce the vram temps.

I see how the design is messed up. The bottom of the thin fins close off the airflow to the aluminum block that dissipates the VRM heat. Airflow to VRMs is very important. This is a good fix. Probably provides more airflow to the fins that are cooling the copper block for the core too.

new2019 said:

I dont get it because , cutting it cant get the temps this low , the reason they have long fins are to increase the surface area so the heat dissipation with be high , but if you cut it its going to become high.
Also because one side of the vram sink is connected with main heatsink the heat will conduct through the fins and dissipate.
The reason may be you got it fixed is:
1. the stock thermal pads were not in good contact with the heatsink
2. those thermal pads may be mis aligned.

OR you could open those closed fins using a small flat screw driver , so it wont have a impact on the core temps and will reduce the vram temps.

Click to expand...

Here's the thing... I had previously removed the heatsink and repasted and replaced the VRM pads with higher performance one's. Little to no difference. Now that I have cut the heatsink not only are the VRM's supplied with a constant supply of direct fan air, the core itself is lower by a few degrees as well. Think of 105 degrees of heat behind that heatsink with nowhere to go but up the small width between the VRM's and the heatsink; it will make the heatsink hotter and less efficient.

All I can say is try it and thank me later.

SOrry mate , I thought it would make the core temp to rise so the vram would automatically .
But if it runs way cooler , then that a mistake the manufactures does.
Or what do you think if you use a small screw driver to open up those fins , than cutting them completely?

Warrior said:

I see how the design is messed up. The bottom of the thin fins close off the airflow to the aluminum block that dissipates the VRM heat. Airflow to VRMs is very important. This is a good fix. Probably provides more airflow to the fins that are cooling the copper block for the core too.

Click to expand...

^this its the truly answer for the issue and indeed a good fix...

I am guessing that the XFX 7970 BE cards that are affected by this are the ones with a non-reference cooler?

My XFX 7970 BE has the reference cooler and even under heavy gaming, I have never seen the VRM temps even get to 50c. The same goes for my Powercolor reference 7970.

cyclone3d said:

I am guessing that the XFX 7970 BE cards that are affected by this are the ones with a non-reference cooler?

My XFX 7970 BE has the reference cooler and even under heavy gaming, I have never seen the VRM temps even get to 50c. The same goes for my Powercolor reference 7970.

Click to expand...

reference cooled cards are always healthy in terms of overall components cooling.. aftermarket cooled generally suffer from the issue of high VRM temperature in some models other models suffer from high vRAM temperature.. and this because generally they just focus on Core Temperature/Noise levels without take into consideration other aspect.. sometimes the heatsink its just too big that prevent the airflow to reach those crucial components..

Thanks for kudos guys. If anyone has done it yet, feel free to post up your experience!

I've got a 7990 that I'll be taking apart tonight and doing this too as well, will post pics and results
when it's done!

new2019 said:

SOrry mate , I thought it would make the core temp to rise so the vram would automatically .
But if it runs way cooler , then that a mistake the manufactures does.
Or what do you think if you use a small screw driver to open up those fins , than cutting them completely?

Click to expand...

Honestly, this was sort of a shot in the dark for me too, so it could very well have made core
temps go up... happy to say it didn't though lol

As for the potential for just prying or straightening the fins out where it flattens at
the bottom, I'm taking apart my 7990 tonight and seeing what I can do with it. It's
definitely vapour cooled (tubes along the entire length of the aluminum heatsink) so
if I can straighten them versus cutting out little chunks here and there, I would much prefer
that.

UPDATE: Regarding the 7990, the cooler MSI has on it is finned all the way through
so air can easily reach the backplate attached to the VRM's. My only hope in reducing VRM
temp any further is by replacing the stock thermal pads with Fujipoly 11W/mk pads.

Ordered up a 1/4 sheet each of Fujipoly 0.5mm and 1mm thermal pads from FrozenCPU.
I'll update again when it arrives in a few days time and I've done the switch on the 7970 and
the 7990!

UPDATE #2: Ok, finally got the Fujipoly 11w/mk thermal pads in and all I have to say is
WOW.

Running the 7970 at stock settings (1000/1425) and fan speed at 50%, I ran Furmark
until temps leveled out. Furmark settings were 1080p and 8xMSAA:

https://imageshack.com/i/f0hb2LLgp

VRM temps stayed at par the entire test. Increasing the fan speed would definitely drop
temps even more, but I'm running an open air setup and 50% is as high as I'd like to go
for gaming. While gaming, the VRM temps are 10 or more degrees lower than the core
at any given time. All with the stock cooling solution, Fujipoly and the modification to the
heatsink so that direct fan air can directly hit the VRM's.

The 7990 had the greatest success however! I don't know if it's because of the triple fan
design (versus the 7970's dual fans) or the copper block being on the hottest row of
VRM's (versus the 7970 which uses aluminum), but here's the same Furmark test run on
it with the fan speeds at only 40%:

https://imageshack.com/i/hjqeXsEap

The VRM's are over 30 degrees cooler than the stock pads on average. Gaming with it
is like having a brand new card, it made an enormous difference and I no longer have
buyers remorse over dropping the $800 for it a year ago.

After my experiences doing these mods, any card I get in the future, new or used, will be
torn down immediately to do a repaste, adjustment to any potential heatsink flaws and
VRM thermal pads replaced with Fujipoly. I can only assume card manufacturers and
engineers have some sort of financial partnership with aftermarket cooling solutions to
produce and sell a product from factory that functions, but barely.

Probably could have just cut out every other group of three and got the same results while maintaining a larger heatsink for the core. Just a thought for next time.

lavaheadache said:

Probably could have just cut out every other group of three and got the same results while maintaining a larger heatsink for the core. Just a thought for next time.

Click to expand...

This is the second time it's been mentioned that somehow cutting off the tail end of the
core heatsink affects the temps in a negative fashion in regards to this particular
brand and model of card... it doesn't. I've shown it to not happen. Before I cut it off, I
physically touched the heatsink in that area with my fingers and it wasn't even hot. The
majority of dissipation occurs nearest the core itself, where the heatpipes are located,
which is on the other side of the heatsink. Under heavy gaming, the temps for both the core
and VRM's don't rise above 65 ish degrees @ 50% fan speed. Before, I was getting 85 degrees plus.

I suppose you COULD cut out every other group of three, allowing a small amount of air
through, but it wouldn't be nearly as effective considering the VRM heatsink runs 90
degrees to the rows you would be cutting.

I think I'll be doing new heat pads in my future to. Even though I have 280x's, re-doing the thermal transfer compounds and materials always improves cooling. And, In regards to cooling in general, airflow is always going to be needed. The original design made a heat pocket, heat couldn't escape, and air couldn't get in. I'll say it again, this is a fantastic finding, and I praise you for sharing it with us.

Warrior said:

I think I'll be doing new heat pads in my future to. Even though I have 280x's, re-doing the thermal transfer compounds and materials always improves cooling. And, In regards to cooling in general, airflow is always going to be needed. The original design made a heat pocket, heat couldn't escape, and air couldn't get in. I'll say it again, this is a fantastic finding, and I praise you for sharing it with us.

Click to expand...

It made nothing for my 280x sadly... same temperatures as day one.. even changing 3 times both thermal pads and core tim with Noctua nt-h1 temps.

Littlestan, or anyone else that did this. Could you please post pics maybe from a little farther back please? MS paint diagram maybe ?

I'm trying to wrap my head around why say, a fan placed beside or behind said cards wouldn't greatly help airflow. It seems at the very least the stock thermal pads were doing a bad job.

Warrior said:

I think I'll be doing new heat pads in my future to. Even though I have 280x's, re-doing the thermal transfer compounds and materials always improves cooling. And, In regards to cooling in general, airflow is always going to be needed. The original design made a heat pocket, heat couldn't escape, and air couldn't get in. I'll say it again, this is a fantastic finding, and I praise you for sharing it with us.

Click to expand...

Right on, happy to have helped in some way!

runudownquick said:

Littlestan, or anyone else that did this. Could you please post pics maybe from a little farther back please? MS paint diagram maybe ?

I'm trying to wrap my head around why say, a fan placed beside or behind said cards wouldn't greatly help airflow. It seems at the very least the stock thermal pads were doing a bad job.

Click to expand...

I've got the 7970's all buttoned up and posted for sale on CL so I can't show you any
more disassembled pics, but I took some additional assembled pics to hopefully clarify
things for you.

Looking directly from the top, you can see the edge of the heatsink that's been cut off
and the end of the VRM heatsink poking out from above the fan assembly:

https://imageshack.com/i/f0GgS0Zej

Take a quick look at the first pic in this thread now; you can see the original unmodified
heatsink hanging over the VRM heatsink with it's closed ended bottom. It's a great way
of joining multiple fins together, but about as conducive to airflow as a closed door is to
an open window.

Back to the top of the fully assembled and modified heatsink, I placed a green post-it
note in the area where the cut off heatsink chunk was to demonstrate the air blocking
nature:

https://imageshack.com/i/exf0fouQj

The next two pics show that there is no practical way to introduce air into the system,
virtually all passages are too narrow or constrained to focus any meaningful airflow into
them using conventional methods:

https://imageshack.com/i/hlRjZyRhj

https://imageshack.com/i/pbb4yRS9j

Hope that clears up the confusion and this somehow guides you in your future modding
endeavors!

Littlestan said:

Hope that clears up the confusion and this somehow guides you in your future modding
endeavors!

Click to expand...

Exactly what I was looking for! Thanks for the clarification. Really makes me wonder what the engineers were thinking(or not thinking of) when this card was finished.

Nice work again & it will make me more inclined to get my hands dirty modding. Thinking things through first of course.

AMD should hire the OP in their division responsible for creating their reference coolers

Good job man, your being really helpful.