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Is this right? RAM appears to run below advertised specs

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  • Memory
  • PNY
  • RAM
  • Product
Last response: in Memory
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June 20, 2011 4:22:17 AM

I just started up Memtest86+ on this new build, but the specs it lists for the RAM seem off compared the advertised specs. Two lines in particular concern me:
Settings : RAM : 778 MHz (DDR3-1557) / CAS : 8-8-8-24 / Dual Channel

and several lines down
- Slot 0 : 2048 MB PC3-10600 - PNY Electronics PNY Technologies, *XMP*
- Slot 1 : 2048 MB PC3-10600 - PNY Electronics PNY Technologies, *XMP*

The advertised specs for these sticks are DDR3 1600 (PC3 12800), CL8. I'll have the results of roughly 8 hours of Memtest86+ in the morning, but, in the meantime, any thoughts, advice, or other info I should pull?

More about : ram appears run advertised specs

a b } Memory
June 20, 2011 5:09:41 AM

Memtest is often wrong on timings and speeds. This is especially true when your system has a new chipset.

That RAM may have several profiles stored in the SPD chip, so Memtest is probably reading one of the slower profiles instead of reading the one that's in use.
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June 20, 2011 1:02:36 PM

Just shy of 9 hours with no errors on Memtest86+. Is there a preferred method of checking the speed and timings on these sticks? I just want to be sure they are performing as advertised.
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Related resources
a b } Memory
June 20, 2011 3:07:05 PM

You can use CPUZ to verify the clocks and timings. It runs in windows.

Note that those advertised specs on your RAM refer to the speeds at which the RAM itself is rated to run. Your memory controller may or may not be able to operate at 1600 MHz (data rate). Anyway, if your RAM is not running at 1600, you may have change a setting in BIOS.
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June 20, 2011 5:32:54 PM

From the CPUZ report:
Chipset
-------------------------------------------------------------------------

Northbridge Intel Sandy Bridge rev. 09
Southbridge Intel ID1C44 rev. 05
Graphic Interface PCI-Express
PCI-E Link Width x16
PCI-E Max Link Width x16
Memory Type DDR3
Memory Size 4096 MBytes
Channels Dual
Memory Frequency 802.4 MHz (1:6)
CAS# latency (CL) 8.0
RAS# to CAS# delay (tRCD) 8
RAS# Precharge (tRP) 8
Cycle Time (tRAS) 24
Command Rate (CR) 2T
MCHBAR I/O Base address 0x0FED10000
MCHBAR I/O Size 19456
MCHBAR registers

Memory SPD
-------------------------------------------------------------------------

DIMM # 1
SMBus address 0x51
Memory type DDR3
Module format UDIMM
Manufacturer (ID) PNY Electronics (7FBA000000000000)
Size 2048 MBytes
Max bandwidth PC3-10700H (667 MHz)
Part number PNY
Manufacturing date Week 18/Year 11
Number of banks 8
Nominal Voltage 1.50 Volts
EPP no
XMP yes
XMP revision 1.2
JEDEC timings table CL-tRCD-tRP-tRAS-tRC @ frequency
JEDEC #1 6.0-6-6-16-23 @ 444 MHz
JEDEC #2 8.0-8-8-22-30 @ 592 MHz
JEDEC #3 9.0-9-9-24-34 @ 666 MHz
XMP profile XMP-1600
Specification PC3-12800
Voltage level 1.650 Volts
Min Cycle time 1.250 ns (800 MHz)
Min tRP 10.00 ns
Min tRCD 10.00 ns
Min tWR 15.00 ns
Min tRAS 30.00 ns
Min tRC 50.63 ns
Min tRFC 110.00 ns
Min tRTP 7.50 ns
Min tRRD 7.50 ns
Command Rate 2T
XMP timings table CL-tRCD-tRP-tRAS-tRC-CR @ frequency (voltage)
XMP #1 6.0-6-6-18-31-2T @ 600 MHz (1.650 Volts)
XMP #2 8.0-8-8-24-41-2T @ 800 MHz (1.650 Volts)

DIMM # 2
SMBus address 0x53
Memory type DDR3
Module format UDIMM
Manufacturer (ID) PNY Electronics (7FBA000000000000)
Size 2048 MBytes
Max bandwidth PC3-10700H (667 MHz)
Part number PNY
Manufacturing date Week 18/Year 11
Number of banks 8
Nominal Voltage 1.50 Volts
EPP no
XMP yes
XMP revision 1.2
JEDEC timings table CL-tRCD-tRP-tRAS-tRC @ frequency
JEDEC #1 6.0-6-6-16-23 @ 444 MHz
JEDEC #2 8.0-8-8-22-30 @ 592 MHz
JEDEC #3 9.0-9-9-24-34 @ 666 MHz
XMP profile XMP-1600
Specification PC3-12800
Voltage level 1.650 Volts
Min Cycle time 1.250 ns (800 MHz)
Min tRP 10.00 ns
Min tRCD 10.00 ns
Min tWR 15.00 ns
Min tRAS 30.00 ns
Min tRC 50.63 ns
Min tRFC 110.00 ns
Min tRTP 7.50 ns
Min tRRD 7.50 ns
Command Rate 2T
XMP timings table CL-tRCD-tRP-tRAS-tRC-CR @ frequency (voltage)
XMP #1 6.0-6-6-18-31-2T @ 600 MHz (1.650 Volts)
XMP #2 8.0-8-8-24-41-2T @ 800 MHz (1.650 Volts)
Both DIMMs are showing "Max bandwidth PC3-10700H (667 MHz)", and the Chipset report shows "Memory Frequency 802.4 MHz (1:6)". The CL, at least, seems to be correct, but what's with the frequencies? The XMP profile (which I turned on in the BIOS) is showing the correct 1600 and PC3-12800 at 1.65V, but down below, on the timings table, #1 is something way off, and #2 shows the correct timings but at 800MHz. Also, this mobo should be able to handle DDR3 1600, no?
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a b } Memory
June 20, 2011 5:39:20 PM

"Memory Frequency 802.4 MHz" This means your RAM is running at 1600 MHz (data rate). Your RAM clock is fine and it looks like it's running at the CL8 timings, which is good.

The "SPD" tab is just reading a little text file which is encoded on the RAM sticks. It doesn't give you any info about how your system is actually running. :)  The "memory" tab in CPUZ is the one that gives you info about how your stuff is running.
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Best solution

a c 347 } Memory
June 20, 2011 5:53:10 PM

Settings : RAM : 778 MHz (DDR3-1557) / CAS : 8-8-8-24 / Dual Channel

Running at 778 * 2 = 1556 MHz which is due to the BCLK fluctuations {normal}. CPU-z reports I/O bus clock and not the Data rate which is 2 clocks per cycle or "DDR3 = Double Date Rate revision 3". Next, "Max Bandwidth" per CPU-z is the e.g i7-9xx spec 1066 MHz / 2 = 533 MHz or Sandy Bridge's 1333 MHz / 2 = 667 MHz spec etc per your CPU. The "JEDEC" are speeds and CAS Timings available and programmed 'SPD' or Intel's 'XMP' in the module(s).

Hope that help! :) 
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June 21, 2011 1:50:57 AM

jaquith said:
Settings : RAM : 778 MHz (DDR3-1557) / CAS : 8-8-8-24 / Dual Channel

Running at 778 * 2 = 1556 MHz which is due to the BCLK fluctuations {normal}. CPU-z reports I/O bus clock and not the Data rate which is 2 clocks per cycle or "DDR3 = Double Date Rate revision 3". Next, "Max Bandwidth" per CPU-z is the e.g i7-9xx spec 1066 MHz / 2 = 533 MHz or Sandy Bridge's 1333 MHz / 2 = 667 MHz spec etc per your CPU. The "JEDEC" are speeds and CAS Timings available and programmed 'SPD' or Intel's 'XMP' in the module(s).

Hope that help! :) 

That's exactly what I needed to know, thanks.
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June 21, 2011 1:51:19 AM

Best answer selected by cortillaen.
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