Hi Folks,
I'd like help understanding the RAM in the as-built Acer Orion Predator (PO3-620-EB13) I just bought (w/2x8Gb pre-installed), and then predict what will happen if I install 2x16 Gb Kingston
DDR4 3200 MHz CL16-18-18 @ 1.35V "XMP Certified" (KF432C16BB1K/32). Notice that the datasheet has a single JEDEC default of "DDR-2400 CL17-17-17 @ 1.2V". I've attached two images showing my current 2x8 GByte Max Bandwidth "DDR4-3200 (1600 MHz)" pre-installed. The part number on the OEM RAM (ACR32D4U2S1ME-8) doesn't have much info online.
I'm a victim of trying to match the installed/advertised "3200 MHz"; so I purchased 2 sticks of 16Gb @ 3200 MHz that are now hard and expensive to return. I understand (after purchasing the 3200 MHz) that 2666Mhz is the recommended RAM speed. My post is more about "How bad will it be if I do it anyway?".
Understanding
(aka N00b Questions)
- Q1. Given the "Memory" tab of CPU-Z shows "1463.2MHz", does that mean the mobo has chosen to use JEDEC #11? Is this expected? Should I not see 1600 MHz (ie JEDEC #14)?
- Q2. Is there somewhere online I can look up the SPD Timings Tables, ideally based on part number? Does all RAM have (at least?) 4 permutations of timings that it will work at?
PredictingI've reviewed several past threads on these boards. I want to summarize what I've learned. If any of the following is not accurate, or current,
please please please correct me. Consider them assumptions I'd like validated or conversations starters.
- Q3. XMP is incompatible with the H470 chipset in my (all?) PO3-620 machines. The outcome is that if you try to use XMP compatible RAM, you'll get some (unknowable?) lower JEDEC default speed. Is this all true?
- Q4. The BIOS is terrible/limited, so we can't manually control RAM timings. The outcome is that the mobo might choose really low speeds and there is nothing I can do about it. Is this still current?
- Q5. Given the above, if I install the 2x16Gb, which scenario is likely to be the outcome?
A0 - 48Gb @ < 1200 MHz - ie the documented 2400 MHz JEDEC isn't the worst case, DRAM frequency for all RAM drops to something terrible as the lowest common-denominator.
A1 - 48Gb @ 1200 MHz - ie the documented 2400 MHz JEDEC default kicks in on the new RAM, DRAM frequency for all RAM drops to 1200 MHz as the lowest common-denominator.
A2 - 48Gb @ > 1200 and < 1454 MHz - Some other (unknowable, but higher than 1200 MHz), RAM timing kicks in on the new RAM, DRAW frequency for all RAM drops to something like 1333 MHz.
A3 - 48Gb @ 1454 MHz - ie the new ram is undocumented but compatible with JEDEC #11 (1454 MHz), so no degradation of DRAM frequency and 48Gb is useable.
B1 - RAM timings are so different, my machine won't boot with both sets installed.
B2 - RAM timings are so different, my machine risks being damaged with both sets installed.
- Q6. - Will I even notice the difference between 1200 and 1454?
- Q7. Given the above, if I installed 2x16Gb and removed the 2x8Gb, which scenario is likely to be the outcome?
C1 - 32Gb @ 1200 MHz - ie the documented 2400 MHz JEDEC default kicks in on the new RAM.
C2 - 32Gb @ ? MHz - there is guaranteed to be some higher undocumented JEDEC default on the new RAM. Can't know until you try.
I have no other mods to this machine.
Thanks for reading and any insights you might be able to teach me and future readers.
