Ramm issue

[bobbydoors]

Hello everyone.
Here's the thing. I have a Dell Optiplex 745 modified system. Among other things I have replaced RAM module with Patriot 4 GB (2+2 Kit). Recently I tested the memory modules with Memtest86 and it came back just fine with no errors. But I've noticed one thing. Memtest reported clock speed at 233 MHz (DDR532) with CAS 1-1-1-31. Processor FSB is also 233 MHz (don't know if it matters).

Now through BIOS i see that the memory modules are at 800 MHz Dual Channel Interleaved. Also CPU-Z reports 400 MHz speed. I understand that in Dual Channel memory types the clock speed is reported as half of the manufacturer report, but the Memtest86 bugs me. 233 MHz is not half.

So, is everything normal or do I need to take care of something?

SYS spec: mbo-intel q9645; cpu-intel core 2 duo 6400 2,13 MHz; ram-patriot 4 GB (2+2 Kit) 800 MHz; psu-ocz extreme 650w.
Also, the BIOS is copletely useless because I'm not allowed to change anything throgh it. Dell made it impossible. And all the drivers, including BIOS are up to date.

Thx

 

[jaquith]

Welcome to Tom's Forum!

Look at the 'Memory' tab in CPU-z then multiply 'DRAM Frequency' * 2 -- that's the speed that the RAM running. I'm assuming it's running at DDR2-533.

 

[bobbydoors]

Unfortunately, these fields are grayed out for me. CPU-Z doesnt detect anything. I've tried to resolve this issue too but no luck so far... CPU-Z displays info on the SPD tab only. Memory tab displays only type and size...nothin else

 

[jaquith]

The 'SPD' only contains the available JEDEC 'SPD' Frequency, CAS Timings, and Voltage information available to the RAM, it has nothing to do with how fast Frequency/CAS the PC is running. It's odd that the 'Memory' tab is grayed-out; often this can happen if you're using the wrong DIMM slots or the RAM is mix-matched causing an error and in some instances unsupported 'MOBO' -- those are the only times that come to mind.

If Memtest showed, DDR2-533 then I'd suspect as I said that's the speed its running -- I assumed you were looking at the 'SPD' tab.

Bottom-line, make sure you're using the correct DIMM slots (if 4XDIMM), otherwise if the RAM passed Memtest (4 or more passes) then I wouldn't be concerned. RAM 'speed' is a function of BOTH Frequency (higher) + CAS (lower). The difference between the speeds isn't that much (1%~2%); see below you'll get the idea:

 

[geekapproved]

Go in bios and make sure your DRAM frequency is set to 400mhz. Also check your timings and voltages are set correctly according to the sticker on the dimms. Auto does not always work properly.

 

[jaquith]

Dell is an OEM BIOS, probably has limited or no OC settings, and for the OP's CPU it's best to leave it at 1:1.

 

[bobbydoors]

Wow. Enough info to process. Long story short. I cannot cahange anything in the BIOS, CPU-Z tab "memory" is grayed out so I can't get any info from there - I don't know why, and I'm still a little confused... Do the ram modules run at 800 MHz or not? And if they do not, is there a way to fix this?

 

[bobbydoors]

And dimm slots in use are fine. I have two options, black pair or white pair. Either is the same.

 

[jaquith]

The RAM is capable of running DDR2-800, but not on your system. Everyone gets 'goo goo eyes' with Frequency but they for some reason ignore CAS; again see the chart. 'Typically' it's the 2nd pair of DIMM slots further from the CPU, and I stated some MOBO's aren't fully supported with CPU-z. All that matters is Memtest.

Analogy:
You have to look at RAM as a whole Frequency {bandwidth} and CAS {pauses} with transmission. Think of it this way a car can instantly go 100 MPH but the Stops are longer (9 sec) vs 75 MPH but the stops are shorter (7 sec) both with a 100 stops in a mile. Further, the CPU however says you can run only 85 MPH.

How long does the car take to drive a mile?

 

[bobbydoors]

So is there any way to clock it up to factory speeds, on my system?

 

[jaquith]

You are at factory speed right now.

If you look at your 'CPU' tab, note the Bus Speed that's what you want your RAM to run at e.g. 266MHz * 2 = DDR2-533 <or> 1:1. Your BIOS probably lacks FSB and CPU Ratio settings.

Again, DDR2-533 CAS 1 vs DDR2-800 CAS 3 is basically the SAME speed. If your PC seems slow then it's not because of the RAM -- it's the CPU, HDD, GPU, etc.

 

[bobbydoors]

No. The pc is fine. I thought that ddr2800 beats ddr2533 no matter what. Guess I was wrong. Anyway, now I'm just curious, if I had larger bus speed, ram would be faster, right? And, could fsb be increased? And, btw, what is "rated FSB" just below bus speed?

 

[jaquith]

You might want to take a minute and review what I posted again. Particularly the graph Frequency vs CAS.

The RAM Frequency will run twice the FSB speed (1:1), BUT at a higher CAS. AGAIN, the 'speed' of RAM is a FUNCTION of BOTH Frequency and CAS. The overall speed translated to performance might increase 0% to 2%. By raising the FSB you would also be overclocking the CPU.

You need to expand your knowledge to know RAM's performance is bound to: CPU's IMC (or Memory Chip Controller (MCC)), RAM Frequency and RAM CAS Timings. Both the RAM's Frequency and CAS are EQUALLY important.

Helpful thread -> http://www.tomshardware.com/forum/305395-30-memory-overclocking

RAM: DDR2-533 CAS 1 vs DDR2-800 CAS 3 is more less the same 'performance'. Folks assume incorrectly RAM is all about Frequency and e.g. 533 vs 800 is 33% increase it is NOT!!!!

---

Here's an example of DDR3-1333 vs DDR3-2133 -> http://www.bit-tech.net/hardware/memory/2011/01/11/the-best-memory-for-sandy-bridge/4

There are similar DDR2 comparisons, just Google.

 

[bobbydoors]

Thank you for a very informant conversation. Few things are a little clearer.

 

[neil9294]

This is a really interesting thread. I have a Dell Dimensions E510 and I have had the very same exprience as bobbydoors. I have 8Gb DDR2 @800MHz installed and the BIOS reads it as 800MHz. The memory speed and timings are greyed out in CPU-Z and Memtest reports the RAM as DDR 533 running at 1-1-1-31. the Dell BIOS does not report CAS timings at all so I have no way of cross referencing the Memtest information to check that it is correct, although if I understand jaquith's posts correctly, they are probably right. I also understand from what jaquith has posted that there is virtually no difference between DDR2 @ 533 1-1-1-31 and DDR 2 @ 800 5-5-5-18 (the SPD timings on my Corsair modules). Is this right? If anyone has any further insights into this issue I would be glad to read them.