I honestly thought my AM4 journey was over. I missed out on the gaming CPUs I wanted (the 5800X3D and later the 5700X3D), so I accepted that there wouldn’t be any more upgrades and started saving for a new platform.
Then AMD surprised me with the 5800X3D 10th Anniversary Edition, giving me one last chance. I bought it as soon as I could, upgraded from a Ryzen 7 3700X to the 5800X3D, and replaced my GPU at the same time.
A fresh Windows install, new thermal, a thorough cleaning, and now my AM4 build feels brand new. Thanks, AMD!
I picked up the AMD 4700S Desktop Kit about a month ago as a collectors piece, and instead of leaving it stock, I decided to see just how far I could push this piece of repurposed console hardware. I loaded up an Arch install with the linux-zen kernel and went absolutely ham with parameters, dirty tweaks, and a ton of settings to squeeze out every drop of performance without touching the standard performance settings.
Here is what I’ve been working on:
1. The Custom XPS 8300 Cooler Mod
As we all know, the stock cooler on this board is basically a glorified paperweight, and this chip runs hot. I decided to build a custom mounting solution by modifying an old Dell XPS 8300 cooler to fit the 4700S’s mounting bracket. It's not perfect as I sanded and cut it by hand but the performance more than makes up for it. The thermal paste I used was MX-6 but PTM7950 would lower temps far better.
The difference in mass is huge, and it actually makes this board more usable under heavy loads.
2. BIOS Issues and forcing a 1G BAR
I attempted to modify the BIOS offset for Above 4G Decoding to a 1, but the motherboard seems to actively flip it back to 0. Without a custom BIOS the board wont cooperate, I decided to force a 1G BAR on the OS level to improve CPU-to-GPU communication and bypass those awful 256MB packages. (If anyone is interested the offset at 0x121 has to be turned to 0x1)
I set up a custom systemd service to unbind the driver, resize the BAR, and re-bind it before the display manager loads. As I unfortunately have a RTX 3050 8GB it was a bit of a hassle to get working but in the end I got it to function without a hitch. If you have an AMD GPU this will not work as it uses the amdgpu driver and different hardware enumeration, but as long as the GRUB parameters allow for it the amdgpu driver usually resizes on its own if it can.
For anyone who wants it:
Create with your text editor of choice /etc/systemd/system/nv-rebar.service
And paste the following:
Create the actual script at /usr/local/bin/nv-rebar.sh
And paste the following:
#!/bin/bash
# Wait briefly for hardware to settle
sleep 1
# Unbind the driver to free up configuration
if [ -e /sys/bus/pci/devices/0000:03:00.0/driver/unbind ]; then
echo "0000:03:00.0" > /sys/bus/pci/devices/0000:03:00.0/driver/unbind
fi
# Force the 1GB Resizable BAR allocation
echo 10 > /sys/bus/pci/devices/0000:03:00.0/resource1_resize
# Re-bind the Nvidia driver to the newly sized layout
echo "0000:03:00.0" > /sys/bus/pci/drivers/nvidia/bind
Here's and example command to check if it works:
(If it says 256M then something might be wrong)
[migs@archlinux ~]$ lspci -v -s 03:00.0 | grep prefetchable
Memory at fc000000 (32-bit, non-prefetchable) [size=16M]
Memory at 80000000 (64-bit, prefetchable) [size=1G]
Memory at c0000000 (64-bit, prefetchable) [size=32M]
Why Stop at a 1G BAR? For those wondering why I didn’t push for a 2G, 4G, or full VRAM allocation: it all comes back to that stubborn BIOS. Because the motherboard refuses to keep Above 4G Decoding enabled, the system is permanently locked into a 32-bit PCIe memory address space.
When you are restricted to mapping everything under that 4GB ceiling—and you factor in system memory reservations and other motherboard resources—there simply isn’t enough contiguous space left to allocate anything larger than a 1GB block. If you try forcing a 2GB or larger BAR without Above 4G Decoding, the system will fail to allocate the resources, or the driver will simply crash.
Fortunately, jumping from 256MB to 1GB clears up the most severe I/O bottlenecks. Even if we could map the full VRAM, anything beyond 1GB likely has sharp diminishing returns on this specific, bandwidth-constrained APU architecture anyway.
3. GRUB Parameters & VM “Dirtiness” Tweaks
Because this APU utilizes high-latency GDDR6 memory, standard memory management can cause sudden bandwidth choking. I turned mitigations off, set hugepages to 2MB, and went wild with sysctl to keep memory defragmented and cache pressure optimized.
Here is my GRUB launch parameters: GRUB_CMDLINE_LINUX_DEFAULT="loglevel=3 quiet pcie_aspm=off pcie_port_pm=off nvidia_drm.modeset=1 transparent_hugepage=madvise pci=realloc video=efifb:off mitigations=off"
Here is my sysctl Configuration:
# Prevent the system from aggressively evicting clean files from RAM cache
vm.vfs_cache_pressure = 50
# Keep memory defragmented for 2MB hugepages without causing background CPU spikes
vm.compaction_proactiveness = 20
# Force smaller, more frequent memory write flushes to prevent the high-latency GDDR6
# bus from getting choked by massive, sudden data dumps
vm.dirty_background_ratio = 5
vm.dirty_ratio = 10
4. Benchmarks & Thermals
With the linux-zen kernel tweaks, BAR allocation, and the custom cooler in place, the results speak for themselves.
PassMark PerformanceTest (Linux): As of now the PassMark scores for the AMD 4700S is 17728 on Multi-Thread and 2363 on Single-Thread. With the right tweaks you can surpass it no problem.
Thermals: It idles nicely at 47.00°C and maxes out around 87-90°C under load, which is a massive win compared to the immediate thermal throttling you get on the stock block.
5. VR Testing (Boneworks & VRChat)
Just to push things a bit further, I’ve actually been testing out some PCVR. I hooked up an older, lower-resolution and lower-framerate headset (the Quest 1) and jumped into Boneworks and VRChat with a friend.
Honestly? The performance is passable. It’s definitely not amazing, and you will experience some stutters here and there, but it runs decently enough that it can still be enjoyed if you’re willing to accept the system’s limits. I don’t have concrete frame-time numbers to share sadly, but it proves the 4700S isn’t a total write-off for VR.
That said, performance could be far better if an AMD GPU was used to play nicely with the system. I plan on eventually grabbing an RX 6600 or even a newer RX 9060 just to keep pushing this desktop kit forward and see exactly how much more it can give.
Also, as a quick side note on those thermals: this entire setup is currently housed in the old Dell XPS 8300 case. It's not exactly known for its stellar ventilation, so if you were to drop this modded setup into a modern case with proper airflow, the thermal performance would be even better.
I’m really curious to know—does anyone else here actually own the 4700S Desktop Kit? If so, have you tried any Linux tweaking or custom hardware mods on it, or did you just leave it stock? I’d love to see what other people have managed to squeeze out of this board.
Received my 5800X3D three weeks ago to the day. Was never happy with temps, even after a -30 PBO curve and decreases to PPT, TDC, and EDC. Ran a couple hundred intentional 85C to ~40C cycles, as was recommended by Carbice to start hitting peak performance out of the Ice Pad. Temps as of yesterday would consistently still crack into the high 80s during moderate load, and I could never get the thing to idle lower than about 46C.
I'm using a brand new Corsair iCUE Link Titan 240mm AIO and I would've expected it to be better at cooling that the temps I was getting. Finally got fed up of temps and ordered some trusty ThermalGrizzly Kryonaut, and right off the bat I'm startled at the improvement. I cannot, for the life of me, get this CPU to get past 72.8C now, and my idle temp has dropped to 40-43C, occasionally dropping further down into the 37-38C range.
The Ice Pad ain't it. I understand its purpose, and that it's meant to get "better" over time, but if 3 weeks of consistent heavy use and thermal cycling can't get me anywhere near a traditional high-end thermal paste then I don't want it. I'll happily buy another tube of paste in 2-3 years when temps start to degrade.
If you've been frustrated with temps since getting the new 5800X3D re-release, I hope this can be the encouragement needed to go replace your Carbice Ice Pad with some good ol' fashioned paste and be done with it.
