What's my RAM? Should I exchange it?

[peemo]

Not so pleased that I can't run my PC133 RAM @ 2-2-2 with a 115Mhz FSB on my Soyo 6BA+IV. I can do 3-3-2 or after a lot of fiddling 3-2-2. The RAM is supposed to be CAS2. PLease help me identify it.

On the RAM chips: M2V64S30DTP JAPAN 00912A02-6

On a sticker: VE16X64PC133

The shop where I bought it says that it should run 2-2-2 at 133Mhz and they offered to exchange it for a 256MB module tested with a PIII733 to run 2-2-2 at 133Mhz.

Should I exchange my current RAM? What do I need to ask about the 256MB module before I buy it?

Thanks.

 

[Ulysses]

Where I come from 'CAS 2' means 'CAS 2-2-2'

 

[peemo]

Well up here in Toronto, you are lucky if you can find a local shop that even knows what CAS Latency is. If you do get someone to order CAS2 SDRAM they usually only guarantee CAS Latency = 2 and nothing about RAS-to-CAS delay or RAS Precharge Time.

By the way, looks like my RAM is Mitsubishi. M2V64S30DTP is a 4-bank x 2,097,152-word x 8-bit. - Single 3.3v±0.3V power supply
- Max. Clock frequency -6:133MHz<3-3-3>, -7:100MHz<2-2-2>, -8:100MHz<3-2-2>
- Fully Synchronous operation referenced to clock rising edge
- 4 bank operation controlled by BA0 &amp; BA1 (Bank Address)
- /CAS latency- 2 and 3 (programmable)
- Burst length- 1, 2, 4, 8 and full page (programmable)
- Burst type- sequential and interleave (programmable)
- Byte Control- DQML and DQMU for M2V64S40DTP
- Random column access
- Auto precharge and All bank precharge controlled by A10
- Auto refresh and Self refresh
- 4096 refresh cycles every 64ms
- LVTTL Interface
- 400-mil, 54-pin Thin Small Outline Package (TSOP II) with 0.8mm lead pitch

Since the series after &quot;JAPAN&quot; on the chip ends in -6, I'm assuming that the RAM is actually rated at 3-3-3. Therefore I was mislead by the who sold it to me as CAS2.

My RAM specs are:

tCLK Clock Cycle Time = 7.5ns
tRAS Active to Precharge Command Period = 45ns
tRCD Row to Column Delay = 20ns
tAC Access Time from CLK (CL=3) = 5.4ns
tRC Ref/Active Command Period =67.5ns

Hey, 5.4ns at CL3 is not bad. What would I gain going to true CAS2 memory? Is it worthwhile? In other words, my original question, should I exchange this RAM?

 

[apoppin]

CAS 2 gives a slight performance increase. As I remember, it is around 1-3% over CAS 3.

Would it be an even exchange? If you are having trouble at 115 FSB, I'd say yes - get the better RAM.

 

[Hyper99]

Yeap it only a slight increase of a few percentage
and trying to use Cas 2 on Cas 3 causes
your computer to pauses every few sec and then lockup.
With Cas3 my memory performances is 134MB/sec
with Cas2 it is is 137MB/sec

 

[peemo]

Thanks for the replies.

Yes, it would be more or less a straight exchange. I would pay just the difference between the cost of the two 128MB modules (which I have had since March) and a new CAS2 256MB module. Should I look for any particular make of chips on the new module? I think the shop has one with NEC chips but I don't know who made the module. Any other key specs I should ask about other than 2-2-2?

I'm not currently running CAS2 RAM @ CAS3 - the contrary. The shop said that I was buying CAS2 but the Mitsubishi specs suggest that it is actually CAS3.

Hyper99, how did you get those performance numbers?

Thanks.