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Old 2016-10-31, 22:19   #1
kladner
 
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Default Being pushed toward a new PC

Over the last several months, I have seen variations in both P95 and mfaktc performance. I won't go into the details, ATM. However, I recently got into a situation in which I realized that the Windows reports of the amount of RAM had changed. Instead of saying 32 GB, it was saying 32 GB, 15.9 GB available. I did some digging, and found references to the other 16 GB being devoted to hardware mapping. This did not make sense, as I was not aware of any hardware changes, and such a division of RAM had not appeared previously.

In the course of trying to understand the situation, I took to reseating, the memory sticks. This led to testing pairs, and then individual DIMMs. To cut to the chase, I seem to have lost the use of the third and fourth memory slots. Any of the sticks will work in the first two slots. I see 16 GB of RAM, but it is only single channel. If a DIMM or DIMMs are in the other two slots, and the first two are empty, the machine beeps "No RAM" at boot. I only ever see 16 GB, single channel, no matter if slots 3 and 4 are populated.

I have now gone through checking the slots for debris, repeated contact cleaning, and installing different DIMMs in different slots. Nothing changes. Oddly, in the Asus BIOS, the GPU-DIMM POST still sees all four sticks, but the Main tab only sees 16 GB. memtest86 sees the same.

I don't mind that much, under my current pursuits, that I can't access half of the RAM. Loss of dual channel operation is devastating.

I'm not quite sure was my next step is. A co-worker recently offered me a Dell, still under warranty, for a really good price. I will have to get more details on that. In an ideal world, I'd be looking at an X99 board and perhaps an i7-5820k, but I'm not sure if that is currently possible.
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Old 2016-10-31, 22:59   #2
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Quote:
Originally Posted by kladner View Post
Over the last several months, I have seen variations in both P95 and mfaktc performance. I won't go into the details, ATM. However, I recently got into a situation in which I realized that the Windows reports of the amount of RAM had changed. Instead of saying 32 GB, it was saying 32 GB, 15.9 GB available. I did some digging, and found references to the other 16 GB being devoted to hardware mapping. This did not make sense, as I was not aware of any hardware changes, and such a division of RAM had not appeared previously.

In the course of trying to understand the situation, I took to reseating, the memory sticks. This led to testing pairs, and then individual DIMMs. To cut to the chase, I seem to have lost the use of the third and fourth memory slots. Any of the sticks will work in the first two slots. I see 16 GB of RAM, but it is only single channel. If a DIMM or DIMMs are in the other two slots, and the first two are empty, the machine beeps "No RAM" at boot. I only ever see 16 GB, single channel, no matter if slots 3 and 4 are populated.

I have now gone through checking the slots for debris, repeated contact cleaning, and installing different DIMMs in different slots. Nothing changes. Oddly, in the Asus BIOS, the GPU-DIMM POST still sees all four sticks, but the Main tab only sees 16 GB. memtest86 sees the same.

I don't mind that much, under my current pursuits, that I can't access half of the RAM. Loss of dual channel operation is devastating.

I'm not quite sure was my next step is. A co-worker recently offered me a Dell, still under warranty, for a really good price. I will have to get more details on that. In an ideal world, I'd be looking at an X99 board and perhaps an i7-5820k, but I'm not sure if that is currently possible.
Perhaps reseat the CPU? I have lost a Memory channel on a system where it turned out the CPU wasn't making good contact on a pin and/or a socket pin was bent. Heat cycles can affect this even if you haven't messed with the CPU itself.
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Old 2016-11-01, 00:16   #3
kladner
 
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Quote:
Originally Posted by airsquirrels View Post
Perhaps reseat the CPU? I have lost a Memory channel on a system where it turned out the CPU wasn't making good contact on a pin and/or a socket pin was bent. Heat cycles can affect this even if you haven't messed with the CPU itself.
I will certainly have a go at it.

However, there is a more complicated story going on, which has involved more than one CPU change. While I was wondering about variable throughput, my Corsair H100i (original model) started going bad. It was so bad by the time I set up the RMA, that I found myself better off with the stock AMD cooler.

When the H100i replacement, a V2 model, arrived, and I was removing the stock cooler to put it in, the heatsink compound yanked the 8350 chip out of the socket. It bent pins on one edge, and trying to straighten them just broke one. Long story short, I ended up with an FX-9590. No problem, I thought at first, as the V2 cooler with the 9590 (4.7 GHz) kept things cooler than the V1 cooler had kept the 8350 (4 GHz).

However, this was the point that I realized that I was getting worse performance from the faster chip. So, there is a definite possibility that something is borked in the CPU socket. I will have to do some more cleaning, digging around and reseating of things.

Thanks for the tip!
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Old 2016-11-02, 03:27   #4
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Quote:
Originally Posted by kladner View Post
...When the H100i replacement, a V2 model, arrived, and I was removing the stock cooler to put it in, the heat-sink compound yanked the 8350 chip out of the socket.
I have found that slightly twisting a heat-sink side-to-side will break the seal created by the compound. It doesn't take much. You'll feel it when it lets go.
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Old 2016-11-02, 04:42   #5
kladner
 
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I have found that slightly twisting a heat-sink side-to-side will break the seal created by the compound. It doesn't take much. You'll feel it when it lets go.
Yeah. I was impatient. That technique is a very good idea.
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Old 2016-11-02, 21:15   #6
chalsall
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That technique is a very good idea.
No, it isn't.

LaurV et al, care to interject?
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Old 2016-12-19, 19:06   #7
kladner
 
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The situation with my system has deteriorated. I cannot run Prime95: it freezes or blue screens. Indications are toward hardware problems. I can run the GPUs. I can run Small FFT torture test, but not the others. This suggests a problem in the memory part of the system. I have stripped down to 1, and then 2 DIMMs, in different slots, but problems persist. I am suspecting that this "Open Box" mobo has problems. I can trade it in at Microcenter, but I am debating whether to try once more with the AMD CPU, or to make the leap to Intel.

I know prices are likely to drop when AMD Zen comes out, but I don't know if I can hold out that long. I have started releasing assignments I haven't started. Unfortunately, there are two which were running on the CPU which are at about 60%. I may have to throw that work away.
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Old 2016-12-20, 00:25   #8
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It does sound like the machine is broken. I would replace the motherboard if possible at no charge. It will be easier to sell when new stuff comes out.

Also, Zen might not be the best for Prime95. The desktop Ryzen chips apparently have only two memory channels and possibly half-speed AVX2, so we'll have to see how the price compares to an i5-6500/7500. So it may be that going Intel now wouldn't be a bad thing.
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Old 2016-12-20, 07:34   #9
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Quote:
Originally Posted by Mark Rose View Post
It does sound like the machine is broken. I would replace the motherboard if possible at no charge. It will be easier to sell when new stuff comes out.

Also, Zen might not be the best for Prime95. The desktop Ryzen chips apparently have only two memory channels and possibly half-speed AVX2, so we'll have to see how the price compares to an i5-6500/7500. So it may be that going Intel now wouldn't be a bad thing.
An i5 and DDR4 dual channel would be a great step up. I lust for a hex i7 with quad channel, but that adds ~50% to the price of the basic components.
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Old 2016-12-20, 09:46   #10
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Originally Posted by kladner View Post
An i5 and DDR4 dual channel would be a great step up. I lust for a hex i7 with quad channel, but that adds ~50% to the price of the basic components.
Even an i3 with DDR4 dual channel would be a decent setup. You'll get >> 50% of i5 performance at roughly half the cost. You'll have to do your homework to see if it actually makes sense compared to an i5.

As a point of reference, my i3 skylake does about 28 Gd/d running 1st time LL on 4 (hyper)threads.
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Old 2016-12-20, 12:10   #11
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Quote:
Originally Posted by kladner View Post
An i5 and DDR4 dual channel would be a great step up. I lust for a hex i7 with quad channel, but that adds ~50% to the price of the basic components.
Yeah, when I built my mini cluster, I went with i5-6600 along with DDR-2133. The memory can't keep up with the CPU, but having the high clocked part should help with resale value. The hex core is much faster (I have access to such a system) with the doubled memory bandwidth, but it isn't the cheapest way to do LL.

I should really look at optimizing the power consumption of the cluster via BIOS settings, under locking, etc.
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