RAM Guide
RAM helps your PC multitask, load games, and run apps smoothly. Learn the main differences between DDR4 and DDR5, how to choose the right memory for your system, and why it's important to check your motherboard compatibility and the motherboard QVL (Qualified Vendor List) before you buy.
DDR4
A reliable, affordable standard used in many previous-generation systems. Great for upgrades and value builds.
DDR5
The current mainstream standard, with higher bandwidth and more upgrade headroom for modern platforms.
Check the QVL
Your board's Qualified Vendor List shows the memory kits the manufacturer tested and verified — the safest way to confirm speed and stability.
Capacity
16GB suits most gaming; 32GB adds headroom for creation and heavy multitasking.
Speed & Latency
Measured in MT/s, with CAS latency as the delay. Compare latency only at the same speed.
Compatibility
DDR4 and DDR5 are not interchangeable. Your board and CPU decide which one fits.
Memory vs Storage
RAM is short-term working memory. An SSD or hard drive is long-term storage.
DDR4
DDR4- Proven value
Common in older and
budget systems- Usually lower cost
DDR5
DDR5- Newer standard
- Higher bandwidth
- Best for newer platforms
Memory = RAM
RAM is your PC's short-term working memory — in fact, the "M" in RAM literally stands for Memory (Random Access Memory). It holds the apps, games, and browser tabs your PC is actively juggling right now, and it clears every time you power off.
Storage = SSD / HDD
Storage (an SSD or hard drive) is your PC's long-term filing cabinet — it's where Windows, your games, photos, and files live, and everything stays saved when the power is off. A big SSD can't make up for having too little RAM, and vice versa.
What memory actually is
Before DDR4 against DDR5, before capacities and speeds, there is a simpler question: what is memory, and why does a computer need it at all? This animated explainer answers exactly that, and it assumes you know nothing going in — which makes it the right place to start on this page.
- What a computer is doing when it “remembers” something, and why that job needs its own hardware
- Why the fastest memory is always the smallest, and the largest is always the slowest — the trade-off every PC is built around
- Why memory forgets everything the moment the power goes off, while a drive keeps it — the distinction the memory and storage section on this page builds on
- How the layers work together, so “more memory” and “faster memory” stop sounding like the same thing
Common memory issues, and how to fix them
The five problems our PC Support team sees most with memory, and the checks that resolve them. Memory is the most common reason a PC will not start after an upgrade, and it is usually seating rather than a faulty module.
Core Concepts
The five things that matter most when choosing memory.
- Memory is not storageRAM is short-term working memory that clears at shutdown — the "M" stands for Memory. An SSD or hard drive is long-term storage for your files.
- DDR4 and DDR5 are not interchangeableThey use physically different slots, and your motherboard and CPU determine which one you can install.
- Capacity first16GB is a solid baseline for gaming and multitasking, 32GB adds headroom for content creation, and 64GB or more suits large video and 3D projects.
- Speed and latencySpeed is measured in MT/s and CAS latency is the delay before it responds. Both help, but only compare latency between kits at the same speed.
- Dual channel, XMP, and the QVLTwo matching sticks beat one of the same total size. Enable XMP (Intel) or EXPO (AMD) for rated speed, and buy from your board’s QVL for the fewest surprises.
What Customers Ask Us
Five questions our PC Support team is asked most about this. Tap any one to open it.
How much memory do I actually need?
For browsing, email and documents, 8GB works and 16GB is more comfortable. For gaming and general use, 16GB as a matched pair is the sensible floor and 32GB is the current sweet spot on a new build. Video editing, 3D work, large datasets and running virtual machines all benefit from 32GB or more. Capacity matters far more than speed for how a PC feels: running out of memory forces the system to fall back on the drive, and that is far more noticeable than the difference between two speed ratings.
Why do people say two modules rather than one?
Because desktop processors read from two memory channels at once. Two modules fill both channels and roughly double the bandwidth available compared with a single module of the same total size — which shows up in games and in anything moving a lot of data. It also matters which two slots you use: with four slots on the board, the manual will name a pair, normally the second and fourth from the processor. The wrong pair costs you that benefit even with two modules fitted.
Can I mix DDR4 and DDR5, or two different kits?
DDR4 and DDR5 cannot be mixed at all — they use physically different slots and your board takes one or the other. Mixing two kits of the same type is possible but often disappointing: modules are tested and matched as a set, and two kits with identical printed specifications can use different memory chips inside. The usual result is that neither reaches its rated speed, and it is a common cause of a PC that will not start after an upgrade. Buying one kit of the total capacity you want avoids the whole problem.
What are XMP and EXPO, and do I need to switch them on?
Yes, or your memory runs slower than you paid for. A kit advertised at, say, 6000 MT/s ships with a conservative default and only reaches its rated speed when you enable its profile in the BIOS — XMP on Intel boards, EXPO on AMD. It is a single setting: find it, choose profile 1, save on exit. Expect the next start to take noticeably longer while the board trains the memory, especially on DDR5. That long blank screen is normal and not a sign anything is wrong.
Why should I buy from the motherboard’s QVL?
The Qualified Vendor List is the set of memory kits the board maker actually fitted to that exact model and tested. It is not a list of everything that will work — it is a list of what has been proven to. Buying from it is the lowest-risk way to avoid a kit that will not train, will not reach its rated speed, or will not start at all. If your kit is not on the list, that is common and usually fine; it simply has no testing behind it. Match by the full part number, since capacity and speed alone do not identify a kit.
Last Updated: July 2026 | Newegg PC Support — Memory Buying Guide
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How much DDR4 do you need?
DDR4 is the previous memory standard. It is inexpensive and plentiful, and it only fits boards built for it — you cannot put DDR4 in a DDR5 board or the other way round.
Running out of memory slows everything down. Speed differences are far smaller than that.
A matched pair runs in dual channel and is noticeably faster than one stick of the same total size.
A kit runs at a slow default until you enable XMP in the BIOS. Easy to miss.In plain terms: 16GB as a pair is the sensible floor for DDR4. Buy one kit rather than mixing sticks.
How much?
Capacity matters more than speed for most people:
Fit them in the right slots. With two sticks on a typical four-slot motherboard, use A2 and B2 — the second and fourth slots outward from the CPU — unless the manual specifies otherwise. Buy one matched kit rather than combining separate kits with the same printed specifications.
Worth knowing
Two things that catch people out:
Do not mix kitsSticks bought separately often refuse to run at their rated speed together.
The most common cause of a PC that will not start after a memory upgrade.
Check the QVLBoards publish a list of memory kits they were tested with.
Not a guarantee, but a kit from the list is the safest choice.
Short version: two matching sticks, 16GB or more, and switch XMP on.
Sources: Microsoft, Windows 11 system requirements · Adobe Premiere Pro requirements · Kingston memory capacity assessor
How much DDR5 do you need?
DDR5 is the current standard and what every new platform uses. It has more bandwidth than DDR4 and it is fussier — four sticks in particular can be hard to run at full speed.
Same rule as DDR4: running out of memory hurts far more than a slower kit does.
DDR5 boards often cannot reach advertised speeds with all four slots filled.
Enable EXPO (AMD) or XMP (Intel) in the BIOS or the kit runs slow.In plain terms: 32GB as a matched pair is the sensible target for a new build. If you need 64GB, buy 2 x 32GB rather than 4 x 16GB.
How much?
Capacity first, then speed:
Fit them in the right slots. Use A2 and B2 — the second and fourth slots outward from the CPU — unless the manual says otherwise, and buy one matched kit rather than combining separate ones. On DDR5, prefer two modules where you can: four can place more load on the CPU’s memory controller and may require a lower speed. A first boot after installing or changing DDR5 can also take longer while the board performs memory training.
Worth knowing
Two things that catch people out:
Four sticks is a compromiseBoards commonly derate a four-stick configuration.
On DDR5 they may not reach the rated speed at all.
First boot takes a whileDDR5 trains itself on first start, which can take a minute or more.
A long first boot after a memory change is normal, not a fault.
Short version: 32GB as two sticks, from one kit, with EXPO or XMP enabled.
Sources: Microsoft, Windows 11 system requirements · Adobe Premiere Pro requirements · Kingston memory capacity assessor
What the QVL is, and how to use it
Every motherboard maker publishes a Qualified Vendor List — the memory kits they have actually fitted to that board and tested. It is not a list of everything that will work. It is a list of what they have proven works.
Tested, not guessed. Every kit on the list was fitted to that exact board and run at its rated speed.
It belongs to one board. The list is per motherboard model and revision — not per chipset, and not per brand.
It grows. Makers add kits as they test them, so read the current list rather than the one printed in the box.In plain terms: a kit from the list is the lowest-risk choice. A kit that is not on it is not doomed — it simply has not been tested by the people who made your board.
Using it, step by step
Three things to do, in order:
Match the full part number. Two kits with the same capacity and speed can use different memory chips inside, and only the exact part number on the list was tested. The digits after the speed are the part that matters.
Worth knowing
Two things that catch people out:
Same kit, different codeManufacturers revise kits and change the part number while the marketing name stays the same.
A near-match is not a match. Check the whole code.
Four sticks are a separate caseA kit listed as 2 x 16GB was tested as two sticks. Two of those kits together is a different electrical load.
If you want 64GB, buy one 2 x 32GB kit rather than two 2 x 16GB kits.
Short version: buy one kit from your board’s current QVL, matched by full part number, and you remove most memory problems before they start.
Where to find yours: the support or specification page for your exact motherboard model on the manufacturer’s site — usually under Support, then Memory Support List or QVL.
Still not sure which kit is right for your board?
The PC will not start after I installed memory
Memory is the most common reason a PC will not start after a change, and seating is the usual cause rather than a faulty module.
Usually one of these: a module not fully clicked in, the wrong pair of slots, a profile set faster than this board manages, or two separate kits mixed together.
Try these in order
Before you open the case: shut the PC down, unplug the power cable, hold the power button for about ten seconds to discharge it, then touch a bare metal part of the case to ground yourself. Never open the power supply itself, and never test or probe anything while it is plugged in.
- Reseat both modules. Open both clips, take each module out, line up the notch and press down evenly until the clips close on their own.You should see: A click at each end and both clips upright.
- Use the pair of slots the manual names. Normally the second and fourth from the processor. The wrong pair can stop it starting altogether.You should see: The PC reach the BIOS screen.
- Try one module on its own. Fit a single module in the slot the manual specifies for one-stick use. Then try the other module in the same slot.You should see: Each module start the PC by itself.
- Clear the memory settings. If it started before with different memory, load optimised defaults in the BIOS so no old profile is being applied.You should see: A normal start, after which you can re-enable the profile.
Still stuck? Stop there rather than forcing anything. Use Chat with PC Support or Request a Callback on this page and tell us which of these steps you have already tried — it saves repeating them.
Windows is not showing all the memory I installed
If the PC starts but reports less memory than you fitted, the missing module is usually present but not making contact — or a setting is holding some back.
Usually one of these: a module seated at only one end, a reserved-memory setting in the BIOS, or a module that works in one slot but not another.
Try these in order
Before you open the case: shut the PC down, unplug the power cable, hold the power button for about ten seconds to discharge it, then touch a bare metal part of the case to ground yourself. Never open the power supply itself, and never test or probe anything while it is plugged in.
- Check the figure in the BIOS as well as in Windows. The BIOS reports what the board can see, which separates a hardware problem from a Windows one.You should see: The same or a different total, which narrows it down.
- Reseat the module that is missing. Press down firmly and evenly until both clips close by themselves. A module can look fitted while one end is proud.You should see: The full amount reported.
- Swap the modules between slots. If the shortfall follows the module, that module is the issue. If it stays with the slot, the slot is.You should see: A pattern that identifies which it is.
- Check the memory-reserved setting in Windows. Press Windows + R, run
msconfig, open Boot then Advanced options, and make sure the maximum-memory box is unticked.You should see: The full amount after a restart.
Still stuck? Stop there rather than forcing anything. Use Chat with PC Support or Request a Callback on this page and tell us which of these steps you have already tried — it saves repeating them.
My memory is not running at the speed on the box
This is normal out of the box, not a fault. Memory runs at a conservative default speed until you switch its profile on.
Usually one of these: the XMP or EXPO profile is not enabled, four modules are fitted, or the board and processor cannot reach that speed with this kit.
Try these in order
- Enable the profile in the BIOS. Look for XMP on an Intel board or EXPO on an AMD one, set it to profile 1, and save on exit.You should see: The rated speed reported after restarting.
- Expect a longer first start. After a memory change, especially on DDR5, the board trains the memory. This can take a minute or more with a blank screen.You should see: It reach the BIOS or Windows on its own — leave it be.
- If it will not start with the profile on, step down. Many boards offer a slightly lower speed preset. Use that rather than the full profile.You should see: A stable start at close to the rated speed.
- Remember four modules are harder than two. Boards commonly run four modules slower than two, and on DDR5 four may not reach the advertised speed at all.You should see: Higher speed with two modules than four, which is expected rather than a defect.
Still stuck? Stop there rather than forcing anything. Use Chat with PC Support or Request a Callback on this page and tell us which of these steps you have already tried — it saves repeating them.
The PC has started crashing since I changed the memory
Instability that begins right after a memory change is usually the memory being asked to run faster than this particular board and processor manage, rather than a broken module.
Usually one of these: a profile that is not stable on this combination, two different kits mixed, or one module genuinely at fault.
Try these in order
- Turn the profile off as a test. Set XMP or EXPO to disabled so the memory runs at its default speed, and use the PC normally for a day.You should see: The crashes stop, which points at the profile rather than the module.
- Run a memory test. Windows has one built in: search for Windows Memory Diagnostic and let it run. It restarts the PC and tests before Windows loads.You should see: A clean result, or errors reported.
- Test one module at a time. If the test found errors, run it again with a single module fitted, then the other, to find which one.You should see: One module pass and the other fail.
- Check the modules are one matched kit. Two kits with the same printed speed can use different chips inside and often will not run together reliably.You should see: Stability with a single matched kit.
Still stuck? Stop there rather than forcing anything. Use Chat with PC Support or Request a Callback on this page and tell us which of these steps you have already tried — it saves repeating them.
The PC takes a very long time to start after a memory change
On DDR5 in particular, a long blank-screen start after fitting or changing memory is expected behaviour, not a fault.
Usually one of these: the board is training the memory, which it does after any change to the modules or their settings.
Try these in order
- Leave it alone for up to five minutes. The board is working out timings for the modules you fitted. Interrupting it means it starts again next time.You should see: It reach the BIOS or Windows on its own.
- Expect it again after changing the profile. Enabling or altering XMP or EXPO triggers another training pass on the next start.You should see: One slow start, then normal ones afterwards.
- If it never gets there, reduce the speed. Load optimised defaults, start it, then re-enable the profile — or use a slightly lower preset if the full one will not train.You should see: A normal start time once it has trained successfully.
- Check the modules are in the right slots. The pair named in the manual, usually the second and fourth from the processor, trains more reliably than other combinations.You should see: A quicker, repeatable start.
Still stuck? Stop there rather than forcing anything. Use Chat with PC Support or Request a Callback on this page and tell us which of these steps you have already tried — it saves repeating them.