Need help understanding GPU memory clock?

[opethcire316]

I am building a new cheap computer and I'm looking at two graphics cards
XFX HD-487A-ZWFC Radeon HD 4870 1GB 256-bit GDDR5 PCI Express 2.0 x16 HDCP
and
HIS H487FN1GP Radeon HD 4870 1GB 256-bit GDDR5 PCI Express 2.0 x16 HDCP

my question is i noticed that the memory clock on the XFX card is 900Mhz, however the HiS has 3600Mhz memory clock. I've been trying to do some research on this but haven't been able to find my answer. I read something about actual clock speed vs ?? (i forgot what it was called) clock speed. and that your actual speed is half of the reported?
If anyone could help clear this up for me I would greatly appreciate it,
also any advice on which one to get would be appreciated too.

Thanks.

[sparkax]

The core clock is the speed of the card itself - say 750-900Mhz.
The memory clock is the speed of the memory chip on the card
-say 3600Mhz.
As for choosing which card to buy-that depends on what performance you want and how much you want to pay.
It is very much a personal choice.

[opethcire316]

Thanks for replying but,
The thing that i'm having a hard time figuring out is that, both of those cards that i listed ( found on newegg) are very very close in price. They have practically the same specs too except when it comes to the memory clock. The XFX is showing that it has 900Mhz (3.6Gbps) and the HiS has 3600Mhz. Does the HiS card really have that much more than the XFX? I thought the 3.6Gbps for the XFX was the same as the 3600Mhz of the HiS card but Gbps and Mhz are completely different? I don't know/understand how two cards of the same type radeon 4870s have that drastic of a difference in just the memory clock speed.

Anymore help would be cool.

[opethcire316]

I just wanted to add that both of the cards core clock are the same at i believe 750 or 800Mhz, the only spec they differ in is the memory clock which appears to be a drastic difference. I think i'm leaning towards the XFX card though I want the one of the two that performs better and don't know if the memory clock is that deciding factor?

[opethcire316]

I found my answer i guess, i was looking at a review website and noticed that they listed the memory clock speed at 3600Mhz, i guess it was either a type on newegg or just a different way to write the same thing. I figured it would be the same or very similar based on the price of both.

[crunchie]

3.6Gbps and 3600Mhz = same :)