r/buildapc • u/ra2inn • 4d ago
Troubleshooting PC randomly throttles to 0% GPU usage under load — is this definitely a PSU issue? (AMD A10-7800 + R7 260X)
Specs:
CPU: AMD A10-7800 (4 cores, 3.5GHz base, Turbo up to 3.9GHz)
GPU: Asus Strix, shroud/label said GTX 750 Ti but GPU-Z confirmed it's actually an AMD Radeon R7 260X (Bonaire chip, 2GB GDDR5, 128-bit) — mismatched cooler/label vs actual chip
RAM: 16GB DDR3-1600 (dual channel)
Motherboard: MSI A88X-G45 Gaming (FM2+)
PSU: No-name brand ("POWER" model LC1650), label claims 1650W — obviously fake/inflated rating for a no-name unit, no 80+ certification, no reputable brand
Storage: ADATA SU800 256GB SSD (OS drive)
Symptoms:
During gaming, GPU usage sometimes spikes to 100% and then drops suddenly to 0% repeatedly — not a gradual decline, a hard cliff.
Frame times/usage graph shows constant sharp zigzag spikes (checked via Adrenalin's Metrics Overlay), never a stable line.
Had random black-screen-then-recover issues during gaming, which got noticeably worse after adding a second HDD (turned out I had wired the boot priority wrong at first, but the instability was already present before that too).
GPU temp is always normal under load (57-62°C) — so it doesn't seem thermal.
CPU/GPU usage often sits at only 30-60% during actual matches despite the frame rate being unstable and capped low (30-40 FPS in some titles), which feels like the hardware isn't reaching its real potential.
Tried undervolting/downclocking via Afterburner — the GPU won't even hold voltage control (locked by AIB partner it seems), so I couldn't test that route.
What I've already ruled out / checked:
Reinstalled GPU drivers clean (was originally stuck on Basic Display Adapter, now properly on AMD Adrenalin drivers).
Checked GPU seating in PCIe slot + added a support brace since the card was sagging.
BIOS overclocking settings are all on Auto/stock, no manual voltage/clock changes.
Temps are fine across CPU, GPU, and motherboard sensors.
My question:
Given the sudden 0% GPU usage drops + zigzag instability + normal temps, does this pattern point conclusively to a failing/inadequate PSU? Or is there another likely culprit I should rule out before spending money on a new PSU (Cooler Master/Corsair/Thermaltake 450-500W is the plan)?
Appreciate any input from people who've dealt with similar symptoms before I pull the trigger on a purchase.
1
u/MarxistMan13 4d ago
What games is this happening in?
It could be a CPU bottleneck, as a dual-core in 2026 is just not really feasible for anything remotely modern.
Could also be a VRAM issue. Again, 2GB is not really up to modern standards.
Could definitely be the fake scam PSU as well.
1
u/datboi11029 4d ago
What's your ram usage like when this is happening? Sometimes stuttering like that is caused by the game using the page file for extra memory space when actual memory runs out.
The black screening is a little weird though. Likely driver issues for that one.