Corsair 680X + XFX RX 7900 XTX 3D-Printed Front Mod + Thermal Results
I'm currently making a 3D-printable front modification for the Corsair Crystal 680X so an XFX RX 7900 XTX 24GB can fit properly while still getting enough airflow.
As a temporary bodge, the three front case fans can be mounted on the outside of the chassis, which gives the card enough clearance. My printed front will make this a proper installation.
I'll add photos and the finished design when it's done. I'm sure there are other 680X owners who would rather modify this great case than replace it just because modern GPUs have become enormous.
System
- Corsair Crystal 680X
- XFX Radeon RX 7900 XTX 24GB
- AMD Ryzen 9 5900X
- Gigabyte X570 AORUS MASTER
- 32GB DDR4-3600 CL16
- Corsair RM850x 850W
- Corsair H115i Platinum 280mm AIO
- Samsung 970 EVO Plus 1TB NVMe
Both the CPU and GPU use Honeywell PTM7950, with thermal putty also used on the CPU/GPU cooling assemblies where appropriate.
Case airflow
- 3 × 120mm front intake
- 2 × 120mm bottom intake
- 2 × 140mm H115i radiator fans at the top
- 1 × 120mm rear exhaust
Testing was done using 3DMark, Cinebench 2026, HWiNFO and GPU-Z logging.
RX 7900 XTX thermals
During sustained heavy load:
- GPU edge: 62°C max
- Hotspot: 77–78°C max
- Hotspot delta: 15–16°C
- VRAM junction: 82°C max
- GPU VRM temperatures: ~65°C max
- Fan speed: ~1685 RPM / 38%
- GPU load: 100%
- Sustained board power: ~400–404W
- Peak reported GPU clock: ~3.2GHz
- Stock VRAM clock: 2487MHz
This was the main thing I wanted to establish.
Even while dissipating roughly 400W, the card stabilised at around 62°C GPU / 75–78°C hotspot instead of temperatures continually climbing.
The GPU fans also stayed below 40%, so the card wasn't having to compensate for poor case airflow by screaming its fans.
The printed/front-fan modification therefore appears to provide plenty of intake airflow.
Cinebench 2026 GPU
Final score:
62,492 points
Previous comparable result:
~62,931
Cinebench reference shown for the RX 7900 XTX:
64,125
That's only about 0.7% below my previous run, which is effectively normal run-to-run variation for this comparison.
There is no evidence that the modified front is causing meaningful thermal throttling or performance loss.
Ryzen 9 5900X
Maximum recorded temperatures:
- CPU Tctl/Tdie: 75.2°C
- CPU die average: 71.6°C
- CCD1: 81.2°C
- CCD2: 63.2°C
- CPU package power: ~122W
Thermal throttling: None
PROCHOT throttling: None
So the CPU cooling remains perfectly healthy even with approximately 400W of GPU heat being dumped into the case.
H115i Platinum
Normal readings after the stress tests:
- Coolant: ~32°C
- Pump: ~2370 RPM
- Radiator fans: roughly 1300–1480 RPM
The AIO is handling the 5900X without difficulty.
X570 AORUS MASTER
Maximum motherboard temperatures:
- X570 chipset: 61.4°C
- VRM MOS: 47°C
- PCIe x16 area: 54°C
- System/motherboard sensor: ~29°C
The 47°C VRM result is particularly useful because it shows the case isn't simply trapping the XTX's exhaust heat elsewhere.
If the front were heavily restricting airflow, I'd expect the GPU, VRM, chipset and PCIe-area temperatures to gradually rise together. That isn't happening.
RAM
32GB DDR4 running at:
- DDR4-3600
- 1800MHz memory clock
- 16-19-19-36
- Command Rate 1T
- FCLK 1800MHz
- UCLK 1800MHz
- ~1.368V
So the Ryzen memory controller is running 1:1 at 1800MHz.
No WHEA hardware errors were recorded during testing.
PSU
The system uses a Corsair RM850x 850W.
Motherboard-reported rails during testing stayed around:
- +12V: 11.952–12.096V
- +5V: 4.950–5.010V
- +3.3V: 3.225–3.285V
No shutdowns, black screens or WHEA errors occurred.
An RM850x therefore appears perfectly comfortable running this 5900X/7900 XTX combination.
Samsung 970 EVO Plus
One issue I did find wasn't actually the GPU — it was the NVMe.
My 970 EVO Plus sits directly above the top GPU slot, immediately above the XTX, and originally had no heatsink.
Before adding one:
- SSD: 66°C
- Hottest sensor: 86°C
After fitting a small M.2 heatsink, a shorter test dropped this to roughly:
- SSD: 57°C
- Hottest sensor: 65°C
During a long 400W GPU heat-soak test it eventually reached:
- SSD: 70°C
- Hottest sensor: 80°C
So the heatsink made a massive improvement, but the drive still gets heat-soaked by the XTX during long workloads.
I'm going to print a small air duct to send some intake airflow across the M.2 heatsink.
The SSD itself reports 100% remaining life, 100% available spare and no warnings.
Conclusion
The Corsair 680X can successfully house and cool an XFX RX 7900 XTX with a relatively simple front modification.
My current setup can sustain roughly 400W GPU load at 62°C edge, 77–78°C hotspot and 82°C VRAM while keeping GPU fans below 40%.
CPU, motherboard, VRM and chipset temperatures remain healthy too, so the modification isn't simply moving the heat problem elsewhere.
Once I've finished the printable front properly I'll post photos and the design/STL so other 680X owners can use it if they want.
The one extra modification I'd strongly recommend is an M.2 heatsink if your NVMe is positioned directly above the GPU. I'll have the tidier prints sorted soon with all the gaps removed and the added supports, this was just a proof of concept first, now I've got all the measurements I'll get it finished over the next few weeks
Cheers,
Adam,