Slow Gigabyte GA-5AX

[Guest]

My server machine has lost 25-30% performance since uping the RAM from 128MB to 256MB. The RAM (2x128MB) and slots (3) are all fine, as using just one of the DIMMS in any one of the slots makes the machine speed back up. I did this for both DIMMS, but once both were re-installed, the brakes went back on! Interestingly, with 256MB installed, I used MSConfig to restrict Windows to use the first 128MB, and the machine sped up again. Is this a level 2 caching problem like the old TX and VX's had with memory over 64MB? If so, this is crazy, as the board can support 768MB. The machine spec is:
GA-5AX (Rev. 5), 256MB, K6-2 550MHz, 100MHz Bus, Voodoo 3 3000 AGP, Win98 SE

Any help or ideas would be appreciated!

<P ID="edit"><FONT SIZE=-1><EM>Edited by Bahamut on 01/31/01 04:37 PM.</EM></FONT></P>

 

[Mordy]

>>Is this a level 2 caching problem?
Yes. Many boards support more memory than they can cache.
I heard a rumor about a workaround: Put a CPU that has L2 cache :K6-3, K6-x+. Maybe you can put more cache/tag on your board? What chipset do you have?

All i can offer you is the truth. Nothing more.<P ID="edit"><FONT SIZE=-1><EM>Edited by mordy on 02/02/01 06:41 AM.</EM></FONT></P>

 

[Guest]

The board runs the ALI chipset.

I've now heard from Gigabyte UK who are suggesting that the problem may be caused by running RAM from different vendors - which is indeed my situation. They offer no other suggestions, so I guess the board is capable of caching at least 256MB, and should not suffer the slowdown I'm getting. So hopefully I can fix this by selling the 2x128MB DIMMS and buying 1x256MB.

Thanks for replying to this post!

 

[Diemos]

Hold on there Bahamut. If I remember correctly the 5ax has only 512k of L2 cache. That means that It can only cache 128megs of ram, regardless of it config or manufacturer. The cpu upgrade idea will work, or you can up the mobo (I would suggest the Epox MVP3-G5 w/ 2meg cache) and that would fix the prob. But changing the memory will not, sorry. Hope I caught you in time, laterz.

"I yam what I yam!"

 

[Guest]

No money lost on this one yet!

I have to say I'm surprised if the chipset will only cache the first 128MB, which is less than 17% of the total RAM the mobo can hold. I've emailed Gigabyte UK asking them "What's the maximum memory range that the board can cache to level 2 cache i.e. can it cache all 768MB if fully populated?." I'll post their response up here.

As for CPU's...I've never heard of the K6-2+, and I've never seen the K6-3 in the UK. It was the chip I wanted to get originally, but it's eluded me to date.

Thanks for the info of the Epox mobo - I'm now looking at their site at http://www.epox.nl/english/index.htm.

But one final thought. My other machine is a PIII 800EB running on a Chaintech 6ATA2 with 256MB PC133 (on a single DIMM) with a GeForce 2 GTS 32MB. The level 2 cache is 256KB on chip compared with the GA-5AX setup which is 512KB on board. The PIII doesn't have the same performnce dip above the 128MB line as the Gigabyte does. But why? Doesn't this suggest that Gigabyte may have been correct about the mixed DIMMS on the board, or that mobo chipset architecture issues are also relevant aswell as the total size of the level 2 cache?

Just another confusing day!

 

[Guest]

OK...I've tested this now with a borrowed single 256MB DIMM and it is definately a L2 caching limitation, with the board only caching the first 128MB of physical memory. I have to say that this is a bit NAFF, as this is less than 17% of the total RAM you can populate the board with. Changing the cpu is not an option (unfortunately), unless someone knows anyone with a secret store of K63s in the UK.

I think that this is something that mobo manufacturers should make clear on the spec of the mobo...so that I can avoid making this kind of mistake/purchase again!