256Mb DDR2 £10.50

Rave

TheChillPill wrote:

Yes, sorry - I didn't word that very well!

Basically, DDR2 has twice the bandwidth as regular ram, so it can handle more data and thus faster. Regular DDR with a clock frequency of 100Mhz will have a data output of 200Mhz. Whereas DDR2 with a clock frequency of 200Mhz will have a data output of 400Mhz and so on.

Nah, not true. There's some aspect of DDR2 that runs faster (so you get marginally faster sustained transfers or something, I forget the exact details), but it's still Double Data Rate memory. DDR1 at 200MHz has an effective clock rate of 400MHz thanks to the data being transferred twice per clock- and so does DDR2 running at 200MHz. If it was transferring double the amout of data per clock than DDR it'd be called QDR;). In general, DDR2 can run up to much higher clockspeeds than DDR1 (with correspondingly higher latencies), but that's not much use unless you're an overclocker.

Not sure I agree with the 'no matter how fast the ram speed is your machine will actually run slower.' bit - unless you are referring to replacing a 512Mb DDR chip with a 256Mb DDR2 chip, in which case you are correct.

Nope- 256MB of RAM is 256MB of RAM whether it's SDR, DDR, DDR2, Rambus or whatever. If you run out of memory space then you have to use the page file on the hard disk, which is an order of magnitude slower. If you had a DDR2 system with 256MB of RAM, but the OS and programs needed, say, 400MB, then a 512MB system is likely to be faster even if it's old SDR memory.

Best way to describe it would be to say that, like-for-like (ie a 256Mb DDR vs a 256Mb DDR2) the DDR2 should work virtually twice as fast.

Nope. All the name DDR2 refers to is that it's the second generation of DDR technology, not that it's a doubling of speed.

HOWEVER- having said all that, this is a very good price, would be ideal for upgrading one of those £99 Dell servers for example. As already stated though, DDR1 and DDR2 are not compatible, so make sure the machine you're buying it for really is DDR2.

TheChillPill

I think you may have misunderstood what I said about replacing a 512Mb DDR chip with a 256Mb DDR2 chip, because your reply to that was exactly the same as I stated. What I was saying was that a DDR2 was going to be faster than a DDR of the same size - not that it would run faster with a 256Mb DDR2.

However, you're point about DDR2 referring to it as simply the 2nd generation isn't correct.

To demonstrate;

DDR - Memory Cell Array outputs 2-bits per clock - Data freq 200Mhz
DDR2 - Memory Cell Array outputs 4-bits per clock - Data freq 400Mhz

Anyway, this is probably more for the techie board ;-)

Rave

Yes, the memory cell array outputs 4 bits per clock, but it runs at (effectively) half the speed of DDR, all else being equal. PC4400 DDR2 will be slower than PC4400 DDR1 because the external data rate (I.E. from the module to the memory controller) is the same, but the DDR2 has higher latencies inside the module.

http://www.lostcircuits.com/memory/ddr3/

Edit: you were indeed saying the same as me about the 256 vs 512 though, sorry about that.

To-poor

TheChillPill wrote:

Not sure I agree with the 'no matter how fast the ram speed is your machine will actually run slower.' bit - unless you are referring to replacing a 512Mb DDR chip with a 256Mb DDR2 chip, in which case you are correct.
QUOTE]

yep, exactly what I mean :beer:

biglugs

Getting back to the original post - I made the mistake of buying cheap memory from Aria before. Didn't work properly, I had to pay to return it. They claimed it DID work and made me pay to have it returned. When it failed again I had to pay to return it. They paid to send a replacement which also failed - I chucked it in the bin and gave up buying cheap memory from them.
It really is the case that you get what you pay for when it comes to PC memory - probably worth paying a few more quid and getting some branded chips. IMO.

To-poor

To be honest, aria are crap and I would only buy from them if ebuyer didnt have what I needed and I was desperate!

tightus_wad

I've got 2 sticks of this stuff in my DELL - ordered on Monday, Arrived tuesday - installed and running -sweet as a nut! Way cheaper than anywhere else 2!

charlie12

TheChillPill - could you please edit your first post with the technical corrections, especially the fact that DDR2 RAM is not backwards compatible with DDR boards.

cheers

TheChillPill

Just done so and made bold - thanks for pointing that out, hadn't realised that I'd done a critical typo there too which could have been misleading!