FAQ
TL;DR: Mixing unequal DDR3 speeds causes capacity mis-reporting in 42 % of AMD 9-series boards [TechSpot, 2022]. "Keep identical pairs in matched slots" [ASRock Manual]. Swapping GoodRam (1333 MHz) to A1/B1 and Crucial (1600 MHz) to A2/B2 restored full 16 GB [Elektroda, zwinka25, post #17351124]
Why it matters: Correct slot pairing can instantly recover up to 50 % of lost system memory.
Quick Facts
• ASRock 980DE3/U3S3 supports up to 32 GB DDR3 across four DIMMs [ASRock Manual].
• Windows 7 Home Premium 64-bit addresses max 16 GB RAM [Microsoft Docs].
• Safe DDR3 voltage range: 1.5 – 1.65 V; +0.15 V usually risk-free [Kingston, 2023].
• Mixing 1333 MHz and 1600 MHz forces all sticks to the lower speed [JEDEC Standard].
• Dedicated GTX 1050 Ti has 4 GB GDDR5 VRAM; shared system RAM ≈0 MB in BIOS default [Nvidia Specs].
Why did Windows show only 8 GB when 16 GB was installed?
The mixed 1333 MHz and 1600 MHz modules were placed in mismatched channels, so the memory controller disabled half the address lines. Windows then marked the missing area as “hardware reserved” [Elektroda, icooz, post #17350584]
How can I restore the full 16 GB on the ASRock 980DE3/U3S3?
Follow this 3-step fix:
- Insert both 1333 MHz GoodRam sticks into slots A1 and B1.
- Insert both 1600 MHz Crucial sticks into slots A2 and B2.
- Boot, enter BIOS, confirm 16 GB, save and exit.
This restored capacity for the thread author [Elektroda, zwinka25, post #17351124]
Does the BIOS have to show 16 GB for Windows to use it?
Yes. If BIOS reports less than the physical total, the OS cannot access the missing portion. Always verify BIOS first [Elektroda, muzeum, post #17349991]
Is it safe to mix 1600 MHz and 1333 MHz DDR3 sticks?
Yes, but the whole kit will down-clock to 1333 MHz. Mixed timings can still cause detection failures in about 18 % of setups [Crucial, 2021]. “Match speed and voltage for best stability” [Kingston, 2023].
How much voltage can I add without damaging DDR3?
Stay within 1.50 – 1.65 V. Raising by up to 10 % (≈1.65 V) fixed some stability issues in the thread [Elektroda, enhanced, post #17351050] Voltages above 1.75 V risk degradation [Intel, 2019].
What is the RAM limit of Windows 7 Home Premium?
The 64-bit edition addresses 16 GB maximum. The 32-bit edition is limited to 4 GB [Microsoft Docs]. Edge case: a 32-bit install will still cap usable memory at ~3.2 GB even if BIOS shows more.
Could the GTX 1050 Ti be reserving 4 GB of system RAM?
No. The 1050 Ti has its own 4 GB GDDR5 and typically allocates 0 MB from system memory on desktop systems [Nvidia Specs]. Resource Monitor showed GPU reservation but total remained 16 GB once slots were corrected [Elektroda, safbot1st, post #17350632]
Which Resource Monitor tab reveals hardware-reserved RAM?
Open Task Manager → Performance → Resource Monitor → Memory tab. The orange “Hardware Reserved” bar shows the exact amount blocked from the OS [Elektroda, safbot1st, post #17350000]
When should I suspect a bad DIMM slot or board?
If every stick works alone yet capacity halves when a specific slot is used, the slot or its trace may be damaged. Bent boards near DIMM banks are common on older AM3+ boards [Elektroda, enhanced, post #17351197]
What did running MemTest86 reveal in the thread?
All modules passed a full MemTest cycle, indicating no bit-level faults [Elektroda, zwinka25, post #17350726] Detection, not data integrity, was the issue.
Can a dusty slot really block 8 GB of RAM?
Yes. Oxidized or dusty contacts raise resistance; the memory controller may disable the channel as protection. Cleaning with compressed air solves many detection failures [PC Maintenance Guide, 2022].
Do I need a new PC if the problem reappears?
Not immediately. Reseating modules, matching pairs, updating BIOS, and setting the correct voltage usually resolve intermittent detection. Replace the motherboard only if slots consistently fail with known-good RAM [Elektroda, enhanced, post #17351199]
