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Slot-A K7 750 with 900 core - overclocking capabilities?

A

athithi

Golden Member
EDIT: I just broke open the plastic case and discovered that I have a 900Mhz core 😀 (well, atleast it goes K7900XXXXXX 🙂 ) As mentioned below, I currently have this CPU FSB OC'd at 825Mhz and plan to buy a GFD from a fellow ATer. Does the 900Mhz core mean I can easily up the multiplier from 7.5 to 9? If so, will my current 110Mhz FSB give me an overclocked speed of 990Mhz? Or should I not bother spending the $20 on a GFD and just stay satisfied with the extremely stable 825Mhz that I now have? I do not plan on investing too much time or effort into cooling my system further - perhaps just get a better heatsink/fan. Any tips for a newbie, folks? 🙂

CPU Details:
AMDK7750MTRXXX A
CPU Serial Number: 2300266XXXXX

I am trying to find out how well this processor overclocks with a GFD. I've managed to run it stable at 825Mhz by increasing the FSB to 110 - that's as high as it would go without locking up - it does go to 863Mhz, but is very unstable at that point. Is there some place where I can find overclocking stats from different batches? http://www.ninjamicros.com/leaderboard.html used to have it, but it is no longer there. I also found a french site K7Core which had this info, but they didn't have it for my week at 750Mhz - plus their English mirror is down too 😀

I'd appreciate any pointers in the right direction 🙂 Thanks!
 
Ooops! I thought I mentioned that 😱 Yes, it is a Slot-A Classic Athlon with 512k of L2 cache! I got these numbers right off of the CPU case 🙂
 
Sorry, thought I could help. I've never had a Slot-A. I jumped from a K6-III 450 socket-7 to an 1Ghz Athlon socket-A.
 
Lucky you 🙂 But I went from a PII-266 to a K7-750 ;-) so, didn't do too bad myself 😀 Thanks anyway!
 
Added more info....grateful for any help on this subject - online resources for Slot-As seem to be disappearing from the web 🙁 TIA!
 
You might want to try the overclockers.com database. My brother was able to overclock his 650MHz all the way to over 1GHz with a goldfingers device.
 
Your problem is not going to be with the core since it's a 900Mhz (it should do at least 900 @ the default voltage) and probable 950 or even 1 Ghz with a small voltage bump.

The limit on the Classic Slot A's is the cache speed. The 750 Mhz Mhz CPU came with a 2/5 speed cache, which runs at 300 Mhz, and requires cache chips rated at 3.3 ns or better. The Athlon 900 & above came with a 1/3 speed cache.

A goldfinger device only allows you to change the CPU divisor & the voltage. If you want to change the cache speed, you need to get the soldering iron out. I've modded several Athlons over the years, but it takes a real steady hand.

Since you are running at 825 Mhz (110 Bus), you are currently limited by your cache or by something else in your system that doesn't like the high bus speed.

Look at your Cache chips to see what speed they are. If you're lucky you will have 2.8 ns which should give you 900 Mhz without changeing the cache divisor (892 actually, but they should handle 900 Mhz). 2.9 ns = 862 Mhz, and 3.0 ns - 833 Mhz.

If you change the cache speed to 1/3, 2.8ns = 1.072 Ghz, 2.9 ns = 1.034 Ghz, 3.0 ns = 1 Gz, 3.3 ns = 918 Mhz


 
Richardito:
The Overclockers.com database was exactly what I was looking for! Though the data is anecdotal it does sound very promising 🙂

Rogue1979:
The link that you gave me is absolutely awesome! It gives a lot of details about the cache limitations which Nutzo has also described!

Nutzo:
There are two chips on either side of the core, are they 256k + 256k? This is the info I was able to get from the surface of those chips:


Samsung 010 0C30
K7C2036154


The site that Rogue1979 gave me does have info on how to find the cache speed but it didn't seem to tally with anything I gleaned from the L2 chips 😕

From Rogue1979's link it appears that my processor is made from the .18 micron die. Is that any more helpful in OCing?

I was using a 128MB PC100 SDRAM along with a 128MB PC133 and a 256MB PC133 chip. Could that be the limiting factor for the 110 bus? I have taken out that PC100 chip since but haven't tried increasing the FSB beyond 110.

Are you suggesting that inspite of the cache's limitations I will still be able to get it to around 900Mhz but from that point my options are limited until I can increase the cache speed? Or are you saying that if my cache is what is limiting me to 825Mhz, then even if I use a GFD I won't be able to push it beyond 825Mhz?

I've already purchased the GFD and I guess the only way to find out the true OCing capabilities of my processor is to actually try it out. But this subject is so fascinating that I can't seem to get enough of it 🙂 Thanks!

Hmm....going through your post a second time (and from the 0C30 from the L2), I get the feeling that my L2 might be 3.0ns - which would result in a top speed of 833Mhz with the L2 at 2/5 speed (which it is for the 750Mhz Classic CPUs). Then the only way to increase it further would be to change the cache speed to 1/3 (which would get me up to 1Ghz) - all this even after I use the GFD to increase the multiplier and/or core voltage. Is this correct? Thanks for any info you can provide on this!
 
My guess is the 0C30 means 3.0 ns, so I doubt you will be able to overclock much unless to change the cache to 1/3.

You would actually be slowing the cache down (in comparison to the CPU)

If your system board allows you to disable the cache, you can see how high your CPU will go with your GFD (Gold Finger Device). Your system will be alot slower without the L2 cahce, but you can see how high the CPU will go, and then decide if modding the cache is worth it.

switching to a slower cache (1/3) will slow the system down a little compared to the 2/5 cache.
You would probably have to get to at least 900 Mhz with the 1/3 cache to see any real increase in speed over what you have now.

I usually like to keep the bus at 112 Mhz or less, since PCI cards, AGP cards, Drives, and even the motherboard itself could be holding you back.

With the cache at 1/3 you should be able to get up to 1 Ghz if the cpu can handle it, but more likely you will only get to around 950.

I would set the GFD to 9 multiplier (900 Mhz) and then increase the bus. You'll get better performance at 9x110 bus (990 Mhz) than 10x100 bus (1 Ghz)
 
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