2x16 GB (32 GB)
For gaming. The right starting point for a new gaming PC, with headroom for the browser, voice chat and updates.
Memory, DDR4 or DDR5
Gaming PC RAM: 2x16, 2x32 or 2x64 GB, and the right slots.
How much memory for gaming, streaming, creative work or running AI locally, which slots two modules go in, and what to check when the PC no longer starts after adding RAM. Then, if you like, we take care of it.
- Buying advice from CHF 30
- Upgrade installation: CHF 120
- No part changed without agreement
Our view
2x16, 2x32 or 2x64 GB: how much RAM?
This is our view as PC builders. Memory makers don't all say the same thing: Crucial writes that 16 GB is enough for most gamers, Corsair recommends 32 GB for gaming.
2x32 GB (64 GB)
To game and stream at the same time, edit videos or work on large creative projects.
2x64 GB (128 GB)
For local AI, large 3D scenes or virtual machines. In DDR5, on a motherboard and processor that accept 64 GB modules.
Two modules rather than four: for the Ryzen 9 9950X, AMD lists DDR5-5600 with two modules, but DDR5-3600 with four. The Ryzen 9 9950X and the Intel Core Ultra 9 285K accept up to 256 GB, and Gigabyte's manual for the X870 GAMING X WIFI7 gives 64 GB per module at most.
Sources: Crucial, memory for gaming · Corsair, RAM and gaming · AMD spec page Ryzen 9 9950X · Intel spec page Core Ultra 9 285K · Gigabyte manual X870 GAMING X WIFI7
DDR4 or DDR5
A motherboard accepts only one type of memory
The notches and pins are not in the same place. Corsair advises against trying to fit a DDR5 module in a DDR4 slot, or the other way round.
AMD's spec page for the Ryzen 9 9950X lists only DDR5, and the ASRock X870 Pro RS manual forbids installing DDR4 in its DDR5 slots.
Before you buy, your motherboard's spec sheet tells you which memory type, what capacity per module and which speeds it accepts.
Sources: Corsair, DDR5 and DDR4 · ASRock manual X870 Pro RS
Two modules
Which slots should two modules go in?
On a motherboard with four slots, two modules most often go in A2 and B2, to run in dual channel. Most often, not always: your motherboard's manual decides.
Two modules in DIMM_A2 and DIMM_B2, a single one in DIMM_A2. ASUS refers to the recommended configuration table in each board's manual.
Two modules in DIMMA2 and DIMMB2, a single one in DIMMA2. MSI notes that the method can vary by motherboard.
On the X870 GAMING X WIFI7, the manual recommends DDR5_A2 and DDR5_B2 for two modules in dual channel.
On the X870 Pro RS, two modules also go in A2 and B2, but a single one goes in B2, where ASUS and MSI say A2.
AMD refers to the motherboard manual and explains that the slots are usually named A1, A2, B1 and B2 starting from the processor.
Our view: follow the recommended memory configuration table in your motherboard's manual. If in doubt, send us its exact model.
Sources: ASUS, memory installation · MSI, memory installation · Gigabyte manual X870 GAMING X WIFI7 · ASRock manual X870 Pro RS · AMD, common boot issues
XMP and EXPO
Running RAM at the speed on its box
XMP (Intel) and EXPO (AMD, AM5 socket) are memory overclocking profiles. Intel advises enabling XMP in the BIOS: the PC then automatically applies the profile's settings.
The speed reached depends on the RAM, the motherboard and the processor (ASUS). Intel warns that changing frequency or voltage can reduce stability; AMD, that running outside its specifications voids its warranty.
The XMP or EXPO profile and a stable frequency are among the points checked in an optimisation. The full performance check (CHF 120) and the optimised build (CHF 270) include the memory profile and a stability test.
Sources: Intel, XMP · AMD, EXPO · ASUS, XMP and EXPO in the BIOS
RAM not detected
The PC no longer starts after adding RAM: what to check
These checks come from AMD, ASUS, Gigabyte, MSI and Crucial guides. Only handle the modules with the PC switched off and unplugged.
1
Wait for the first start
With DDR5, some boards ‘train’ the new memory on the first start: the screen can stay black for up to 15 minutes according to Crucial. Leave the PC on during that time.
2
Reseat the modules
A DRAM LED that stays on signals missing or faulty memory (ASUS). Modules pushed fully home, in the slots the manual recommends, clean contacts.
3
One module at a time
Start with a single module, then add the others one by one: that shows which module or slot is at fault.
4
BIOS and compatibility
A clear CMOS restores the factory settings, XMP or EXPO profile included; the method is in the manual. A BIOS update can add support for new modules, and the board's QVL list says which kits have been tested.
Still nothing? The workshop diagnosis at CHF 60 checks the RAM, the BIOS, the XMP or EXPO profile and the start-up, then you get the cause and the price of the next step. Blue screen MEMORY_MANAGEMENT or WHEA: see our guide to error codes.
Sources: Crucial, DDR5 training · Gigabyte, B650 AORUS ELITE AX BIOS notes · ASUS, Q-LED indicators · AMD, common boot issues · MSI, memory installation
Prices
Advice, installation or diagnosis
The price covers the service, excluding components: you buy the kit directly from the retailer. The work to be done and its price are confirmed beforehand.
Buying advice
30 CHF
- FPS/screen goal
- GPU/CPU/RAM/SSD priority
- Useful budget
- Simple shopping list
Upgrade installation
120 CHF
- Part installation
- BIOS if needed
- Clean drivers
- Temperature/FPS tests
Workshop diagnosis
60 CHF
- Black screen or boot loop
- RAM / SSD / power supply check
- BIOS and display check
- Most likely cause
Full validation at CHF 60 to check compatibility and what bottlenecks the processor or RAM before buying. The XMP or EXPO profile is also checked in the full performance check at CHF 120, with a stability test.
FAQ
Frequently asked questions
2x16 or 2x32 GB for gaming?
Our view: 2x16 GB for gaming, 2x32 GB if you stream, edit videos or keep lots of applications open. Crucial writes that 16 GB is enough for most gamers, Corsair recommends 32 GB: the makers' views differ.
Can I add two modules to my current kit?
It can work, but it isn't guaranteed. Corsair advises against combining several kits, even of the same speed, and ASUS recommends modules from the same kit. With four modules, the official speed also drops. Our view: a two-module kit of the capacity you want.
Which slots should two modules go in?
Most often A2 and B2 on a board with four slots, but your motherboard's manual decides: on the ASRock X870 Pro RS, for example, a single module goes in B2.
Should I enable XMP or EXPO?
For the RAM to run at the speed stated on its box, generally yes. It is overclocking: stability is checked after enabling it, and if the PC no longer starts, a clear CMOS restores the factory settings.
How much RAM for local AI?
Our view: the graphics card's memory counts first. 64 or 128 GB of RAM helps when a model doesn't fit entirely in VRAM, at the cost of speed.
Sources: Corsair, mixing kits · ASUS, XMP and EXPO in the BIOS
Going further
Related pages
Graphics card and VRAM
For a new PC: the spec pages of current cards and VRAM for your screen.
See the VRAM pageThe PC no longer starts
Black screen, boot loop or an indicator light stuck on the motherboard.
See the first checksGaming PC upgrade
Graphics card, processor, RAM or SSD: which part to change first.
See the upgrade