Review : MSI R7870 Hawk under DOD


MSI R7870 Hawk under cold:

Card preparation:

The first step will be to remove the cooling system in order to isolate the PCB from the cold. To do this, we will use charcoal gum on the front and back of the PCB. Our cooling system goes down to -50°C which will leave the GPU always at negative temperatures. The principle of insulation is to avoid having water in contact with the electronic components but here there is no risk. We also had to use a small adapter to put on the graphics chip to ensure a perfect contact with our DOD.

The difficulty in isolating this model lies in the presence on the back of the PCB of the MSI GPU Reactor, an additional mini-board attached to the back of the graphics card offering a voltage up to 5 times higher but with a cleaner signal which greatly improves the overclocking capabilities of the card. The MSI GPU Reactor is easy to install or remove.

But what is the DOD?

When I post pictures on our Discord, I get quite a few questions about my DOD also called phase change system. This one was made by Piotres and sent directly from Poland in May 2013 and as you can see, it is still perfectly operational.

We won’t go into the technical terms, but the basic principle is to provide cold at the end of the evaporator which will be in contact with either a processor or a GPU. The temperature at the evaporator goes down to -54°C at no load and during our tests with the R7870, the temperature goes up to -45.5°C, which leaves the chip at negative temperatures as GPU-Z indicates. You can see it here in operation on an Intel i9-9350K processor associated with an EVGA Z390 DARK motherboard.

Let’s use the GPU mount and attach it to our MSI R7870 Hawk in order to start the cold tests. The fan allows us to blow some fresh air on the power stage of our graphics card. For this first series of tests, we did not use any radiator on it.

What do the tests show?

The test configuration consists of an i9-13900KS overclocked to 5.8 GHz, a Teamgroup 7200 MT/s memory kit overclocked to 8000 MT/s CL34, all installed on a ROG Maximus Z790 APEX motherboard. The idea will be first to look for the maximum ” benchmarkable ” frequency under Time Spy by pushing the voltage to 1.35 volt which translates into 1.33 volt on the multimeter. In the next few days, we will try to find ways to exceed this voltage in order to try to go higher in frequency. The idea will then be to chain the benchmarks by crossing our fingers. We have opted for those that score in the 3DMark series.

Finally, the limit is around 1500/1525 MHz for the GPU and still 1600 MHz for the memory. Good news, the cold does not seem to disturb our Hynix memory chips. Despite a voltage of 1.33 volts, the graphics chip does not heat up too much and allows us to keep negative temperatures during all benchmarks.
And here are all the results obtained during this first session.

On these first six benchmarks, we were able to take the first place five times except for 3DMark Fire Strike Ultra where our graphic score is very bad without really knowing why. So it’s quite positive since this first session allowed us to score 127 points. We will do a second session very soon, maybe under LN2 if we manage to unlock the voltages above 1.35v and to deal with older benchmarks. Until then, come and share your experiences on our Discord and see you soon for the cold run of an old GPU!