A+ Guide to Hardware: Managing, Maintaining, and Troubleshooting, Sixth Edition

1. A+ Guide to Hardware: Managing, Maintaining, and Troubleshooting, Sixth Edition Memory

2. Objectives • Learn about the different kinds of physical memory and how they work • Learn how to upgrade memory • Learn how to troubleshoot problems with memory A+ Guide to Managing and Maintaining your PC, 6e

3. Introduction • Memory technologies have evolved rapidly • Study development to grasp current technology • Memory-related tasks performed by a PC technician • Upgrading memory • Adding more memory to a system • Troubleshooting problems with memory A+ Guide to Managing and Maintaining your PC, 6e

4. Memory Technologies • DRAM (dynamic random access memory) • Holds data and instructions used by CPU. Main memory. • Volatile (data does not persist after PC is turned off) • Needs to be “refreshed” a minimum of once every 64 ms (DDR2) • SRAM (static random access memory) • Volatile • Does not need to be refreshed • Used for cache memory (it’s faster than DRAM) • ROM (read-only memory) • Somewhat of a misnomer. Most types of ROM can be written to. • In firmware on motherboard; e.g., ROM BIOS • Non-volatile (retains data after PC is turned off) A+ Guide to Managing and Maintaining your PC, 6e

5. How DRAM Works • http://computer.howstuffworks.com/ram.htm A+ Guide to Managing and Maintaining your PC, 6e

6. Figure 7-1 DRAM on most motherboards today is stored on DIMMs A+ Guide to Managing and Maintaining your PC, 6e

7. RAM Technologies (continued) • Differences among DIMM, RIMM, and SIMM modules • Width of the data path each module accommodates • The way data moves from system bus to the module • Older DRAM worked asynchronously with system bus • Newer DRAM works synchronously with system bus • Retrieves data faster as it keeps time with system clock • Goal of each new technology • Increase overall throughput while retaining accuracy A+ Guide to Managing and Maintaining your PC, 6e

8. Types of memory modules A+ Guide to Hardware, Sixth Edition

9. Older Memory Modules A+ Guide to Managing and Maintaining your PC, 6e

10. SIMM Technologies • SIMMS have a 32-bit data path • Speeds (access times): 60, 70, 80 nanoseconds (ns) • Smaller number indicates greater speed • Components making up the access time • Processor requests the data • Memory controller locates data on the SIMM • Data is placed on the memory bus • The processor reads the data off the bus • Memory controller refreshes memory chip on SIMM A+ Guide to Managing and Maintaining your PC, 6e

11. DIMM Technologies • DIMM (dual inline memory module) • Has independent pins on opposite sides of module • Can have memory chips on one or two sides • Has 168, 184, or 240 pins on edge connector • Has a 64-bit data path and holds 8 MB - 64 GB RAM • Synchronous DRAM (SDRAM) • Has two notches, and uses 168 pins A+ Guide to Managing and Maintaining your PC, 6e

12. DIMM Technologies • Double Data Rate SDRAM • Also called DDR SDRAM, SDRAM II, DDR • Two times faster than SDRAM • DDR2 SDRAM • Faster than DDR and uses less power • DDR3 SDRAM • Faster than DDR2 and uses less power • DDR2 and DDR3 • Use 240 pins • Not compatible: use different notches A+ Guide to Hardware, Sixth Edition

13. DIMM Technologies (continued) • Buffered and registered DIMMs • Hold data and amplify a signal before data is written • Unbuffered DIMM: no support of buffers or registers • SDRAM modules use registers • FB-DIMM is fully buffered • Notches on module indicate supported technologies • Dual channeling • Controller communicates with 2 DIMMs at same time • Example: two 64-bit DIMMs form 128-bit data path • DIMM pairs must have same size, speed, features A+ Guide to Managing and Maintaining your PC, 6e

14. DIMM Technologies • Quad channeling • Introduced with Intel Sandy Bridge chipsets and processors • Using eight memory slots: • Processor can access four slots at a time Figure 4-39 The Intel Desktop Board DX79T0 has eight memory Slots and supports two quad channels A+ Guide to Hardware, Sixth Edition

15. The positions of two notches on a SDRAM DIMM identify the type of DIMM and the voltage requirement and also prevent the wrong type from being installed on the motherboard A+ Guide to Managing and Maintaining your PC, 6e

16. Using dual channels, the memory controller can read from two DIMMs at the same time A+ Guide to Managing and Maintaining your PC, 6e

17. RIMM Technologies • Direct Rambus DRAM (RDRAM or Direct RDRAM) • Uses RIMM memory modules • Expensive and slower than current DIMMs • C-RIMM (Continuity RIMM): placeholder module • Concurrent RDRAM: not as fast as Direct RDRAM • Rambus does not actually make RIMMs • Licenses technology to memory manufacturers • Obsolete, but might still be found on older computers A+ Guide to Managing and Maintaining your PC, 6e

18. RIMM A+ Guide to Managing and Maintaining your PC, 6e

19. Error Checking and Parity • Bank: smallest group of working memory chips • Example: eight memory chips used in 8-bit data path • Parity: error-checking based on an extra (ninth) bit • Odd parity: parity bit is set to make odd number of ones • Even parity: parity bit set to make even number of ones • Parity error: number of bits conflicts with parity used • Example: odd number of bits read in even parity system • ECC (error-correcting code) • Detects and corrects an error in a single bit • Application: ECC makes 64-bit DIMM a 72-bit module A+ Guide to Managing and Maintaining your PC, 6e

20. Figure 7-6 Eight chips and a parity chip hold nine bits that represent the letter A in ASCII with even parity A+ Guide to Managing and Maintaining your PC, 6e

21. CAS Latency and RAS Latency • Two ways of measuring speed • CAS stands for “column access strobe” • RAS stands for “row access strobe” • Both types measure read/write clock cycles • Two or three clock cycles per column or row of data • CAS latency is used more than RAS latency A+ Guide to Managing and Maintaining your PC, 6e

22. Tin or Gold Leads • Connectors inside memory slots are tin or gold • Edge connectors on memory modules follow suit • Tin leads should match tin connectors • Gold leads should match gold connectors • Prevents corrosive chemical reactions between metals A+ Guide to Managing and Maintaining your PC, 6e

23. Memory Speeds • Measures: ns, MHz, PC rating, CAS or RAS Latency • Example: SDRAM, DDR, and RIMM measured in MHz • PC rating: total bandwidth between module and CPU • Example: 200 MHz x 8 bytes = 1600 MB/sec = PC1600 • Factors to consider when looking at overall speed: • How much RAM is installed and the technology used • Speed of memory in ns, MHz, or PC rating • ECC/parity or non-ECC/nonparity • CL or RL rating • Use of dual channeling A+ Guide to Managing and Maintaining your PC, 6e

24. How to Upgrade Memory • The basic technique: add more RAM modules • Problems solved with new memory: • Slow performance • Applications refusing to load • An unstable system • Note empty memory slots on most new computers • Accommodate new DIMM or RIMM A+ Guide to Managing and Maintaining your PC, 6e

25. How Much and What Kind of Memory to Buy • Questions to ask before performing an upgrade: • How much memory do I need? • How much RAM is currently installed in my system? • How many memory modules are currently installed? • What kind of memory modules are currently installed? • How much memory can I fit on my motherboard? • What kind of memory can I fit on my motherboard? • How do I select and purchase the right memory? • Refer to system utilities to determine capacity • Motherboard documentation guides choice of add-ons A+ Guide to Managing and Maintaining your PC, 6e

26. Figure 7-16 Selecting memory off the Crucial Web site A+ Guide to Managing and Maintaining your PC, 6e

27. Installing Memory • Follow safety procedures when installing RAM • Example: always use a ground bracelet as you work • Installing SIMMs • Module slides into slot at an angle • Make sure each module is secured to slot • Verify that POST memory count includes new module • Installing RIMMs • Install modules in this order: bank 0, bank 1 • Remove the C-RIMM (placeholder) filling the slot • Use notches to help orient module in the socket A+ Guide to Managing and Maintaining your PC, 6e

28. Figure 7-18 Installing a SIMM module A+ Guide to Managing and Maintaining your PC, 6e

29. Figure 7-19 Install RIMM modules in banks beginning with bank 0 A+ Guide to Managing and Maintaining your PC, 6e

30. Installing Memory (continued) • Installing DIMMs • Pull out the supporting arms on the sides of the slot • Use notches on the DIMM edge connector as a guide • Insert the DIMM straight down into the slot • Ensure that supporting arms lock into position • New installations are generally uncomplicated • Usually involves just placing memory on motherboard • Older computers may need change to CMOS setup • If new memory not recognized, try reseating device A+ Guide to Managing and Maintaining your PC, 6e

31. Figure 7-20 Installing a DIMM module A+ Guide to Managing and Maintaining your PC, 6e

32. Difference between DDR types A+ Guide to Managing and Maintaining your PC, 6e

33. PC Rating DDR3 and DDR4 (Double Data Rate 3 and 4) PC3-8500 PC3-8500 = DDR3-1066 = 1066 MHz PC3-10600 = DDR3-1333 = 1333 MHz PC3-12800 = DDR3-1600 = 1600 MHz PC4-17000 = DDR4-2133 = 2133 MHz PC4-21300 = DDR4-2666 = 2666 MHz PC4-25600 = DDR4-3200 = 3200 MHz A+ Guide to Managing and Maintaining your PC, 6e

34. PC rating • DDR2 (Double Data Rate 2)PC2-10000 = DDR2-1250 = 1250MHzPC2-9200 = DDR2-1150 = 1150MHzPC2-9136 = DDR2-1142 = 1142MHzPC2-8888 = DDR2-1111 = 1111MHzPC2-8800 = DDR2-1100 = 1100MHzPC2-8500 = DDR2-1066 = 1066MHzPC2-8000 = DDR2-1000 = 1000MHzPC2-7200 = DDR2-900 = 900MHzPC2-6400 = DDR2-800 = 800MHzPC2-6000 = DDR2-750 = 750MHzPC2-5400 = DDR2-675 = 675MHz*PC2-5400 = DDR2-667 = 667MHz*PC2-5300 = DDR2-667 = 667MHz*PC2-4300 = DDR2-533 = 533MHz*PC2-4200 = DDR2-533 = 533MHz*PC2-3200 = DDR2-400 = 400MHz*PC number varies based upon manufacturer labeling A+ Guide to Managing and Maintaining your PC, 6e

35. PC RATING DDR RATING CLOCK RATEDDR (Double Data Rate)PC-4400 = DDR-550 = 550MHzPC-4000 = DDR-500 = 500MHzPC-3500 = DDR-433 = 433MHzPC-3200 = DDR-400 = 400MHzPC-2700 = DDR-333 = 333MHzPC-2100 = DDR-266 = 266MHzSDRAM (Plain)PC RATING CLOCK RATEPC133 = 133MHzPC100 = 100MHzPC66 = 66MHz (very old) A+ Guide to Managing and Maintaining your PC, 6e

36. Timing Numbers • (IE 2-3-3-5-1T) Here's a brief rundown of what these numbers are:2 = CAS Latency (Column Address Strobe)3 = tRCD (RAS or CAS Delay)3 = tRPD (RAS Precharge)5 = tRAS (Number of clock cycles between bank active command and the issuance of a precharge command)1T = Command Rate (Per row activate command) A+ Guide to Managing and Maintaining your PC, 6e

37. Troubleshooting Memory • Common problems: • Boot failure • A system that hangs, freezes, or becomes unstable • Intermittent application errors • General Protection Fault (GPF) errors • Caused by memory errors in Windows A+ Guide to Managing and Maintaining your PC, 6e

38. Upgrade Problems • Dealing with unrecognized add-on or error message • Remove and reinstall the memory module • Check for the suitability of the module for the board • Ensure that the module is the correct size • Remove the module and check for error message • Test the module in another socket • Clean the module edge connectors • Try flashing BIOS A+ Guide to Managing and Maintaining your PC, 6e

39. Recurring Problems • Symptoms of an unreliable memory: • The system locks up • Error messages about illegal operations often display • General Protection Faults occur during normal operation • Some troubleshooting tasks • Run updated antivirus software to check for viruses • Replace memory modules one at a time • Try uninstalling the new hardware • Test, reseat, or replace RAM • Verify that virtual memory settings are optimized A+ Guide to Managing and Maintaining your PC, 6e

40. Summary • RAM categories: static RAM (SRAM), dynamic RAM (dRAM) • Modules used to store DRAM: SIMM, DIMM, RIMM • Synchronous DRAM (SDRAM): moves to the beat of the system clock • Simple parity checks identify one corrupted bit • Error correcting code (ECC) detects and corrects one flipped bit A+ Guide to Managing and Maintaining your PC, 6e

41. Summary (continued) • Memory speeds are measured in ns, MHz, PC rating, CAS or RAS Latency • When upgrading memory, use the type, size, and speed the motherboard supports • New modules should match those already installed • Install new modules by inserting them into the appropriate slots • When troubleshooting, first try the simple technique of reseating the module A+ Guide to Managing and Maintaining your PC, 6e