The Obsidian Series 250D "God Lives Underwater" Build Log Part 5: Overclocking and Thermals

Having finished assembling the Obsidian 250D "God Lives Underwater" build, it came time to power it on. This could easily have just been a showpiece to prove that the hardware at least fits in the case, but we do want to take it as far as we can within reason. This is doubly true when you remember that we've put an AMD Radeon R9 290X under water; a card that used to essentially throttle itself with the stock manufacturer's cooler should now essentially be free of thermal constraints.

Before we get into optimization, a refresher on the components we selected for this build:

• Intel Core i7-4770K CPU (3.5GHz quad-core with Hyper-Threading)
• Diamond AMD Radeon R9 290X (Reference Design, up to 1GHz on the GPU, 5GHz GDDR5)
• ASRock Z87E-ITX Motherboard
• 8GB (2x4GB) Corsair Vengeance Pro DDR3-3000 CAS 12
• 2x Corsair Neutron GTX 120GB SSD in RAID 0
• Corsair AX860i 860W 80 Plus Platinum Power Supply

And the cooling kit we chose:

• AlphaCool NexXxoS ST30 240mmx30mm and UT60 140mmx60mm Radiators
• Koolance RP-1250 Pump/Reservoir Combo
• EKWB EK-Supremacy CPU Waterblock
• EKWB EK-FC R9-290X GPU Waterblock
• Koolance Compression Fittings
• 2x Corsair AF120 Red LED Fans
• 1x Corsair AF140 Red LED Fan

I've documented the assembly extensively. In practice, the system actually works remarkably well. I wasn't entirely certain the cooling capacity would be adequate, and admittedly I had some reservations about opting for the flair of the Airflow Series LED fans as opposed to the improved performance of our SP120 Static Pressure fans. This was mostly paranoia; my experience with my own loop at home and Arctic Cooling's Accelero Hybrid suggested to me that if a 120mm radiator was more than adequate for a ~190W GeForce GTX 680, a 240mm and extra thick 140mm should be plenty for a 300W AMD Radeon R9 290X and 84W Intel Core i7-4770K.

After getting Windows 7 Ultimate SP1 64-bit installed on the RAIDed SSDs, I set to work getting a feel for the performance of the system and then how far I could push it. The DDR3-3000 kit's XMP unfortunately didn't work with this ASRock board; DDR3-3000 requires tweaks to not just memory speed and timings, but also to the system's BClk, something I just wasn't able to coax out of this board and CPU. In retrospect I probably should've gone ahead with the ASUS Maximus VI Impact, PWM riser and all, as ASRock's BIOS had a more confusing layout than ASUS's does. Either way, since I wasn't able to get the CPU stable at the ludicrous DDR3-3000, I had to settle for DDR3-2933 CAS 12, which ran perfectly fine. Note that since the memory is already rated for this speed (and beyond), I left the system at DDR3-2933 for both stock and overclocked settings.

Overclocking Haswell is quickly becoming one of my least favorite things to do. Intel's new chips are fussy, and they run very hot. This particular specimen of i7-4770K was able to get up to 4.3GHz at 1.265V; 4.4GHz was probably doable but would require too much additional voltage (and in turn probably delidding to keep heat from building up under the heatspreader.) Intel's decision to cheap out and use TIM instead of solder under their heatspreaders continues to haunt us.

AMD's Radeon R9 290X was a bit kinder. I was able to get an additional 100MHz out of the GPU itself for an even 1.1GHz, which is pretty much in line with what other people are seeing. More impressively, the GDDR5 was able to overclock up from its stock 5GHz to a full 6GHz. The R9 290X isn't especially memory bandwidth limited, but odd corner cases where that may come into play are essentially dealt with.

You can see thermal performance with the fans and pump running at full bore is pretty impressive. There's only so much that can be done about Haswell's crappy TIM, which is why the CPU is still hitting high temperatures under overclocked load, but the real success story is the R9 290X. A card that cooks itself until it reaches 95C and then throttles under its stock cooling now isn't breaking 55C under sustained load, even after overclocking. To me, this continues to be the real draw of watercooling (besides it just looking neat): getting graphics card temperatures under control without generating tremendous noise.

System performance after overclocking is up roughly 10% across the board. The Radeon no longer has to worry about thermals, so even its stock performance is higher than typical of a reference 290X.

Note that I was also able to substantially reduce pump noise and fan speed without significantly affecting system temperatures. OCCT pushes the CPU cores to almost 90C, and the R9 290X starts to push 60C, but this is with the pump running at about 25% power and the fans at about 50%. The main offender in terms of noise is actually the pump; the fans themselves generate very little noise and the pitch is low, while the pump is more high-pitched and noticeable.

It's being able to achieve these kinds of results with manageable temperatures and low noise that makes custom loop watercooling appeal to me. It's true that it's expensive and does require maintenance and a little bit of risk, but the rewards are evident. The fact that you can put a system this beastly into an Obsidian 250D speaks to the appeal of the chassis itself. It's tough to shoehorn everything in, but it can be done, and the net result is both attractive and powerful.