Topic: IS GHASH.IO Cheating Miners? Paying LESS THAN 50% of expected? (Read 7008 times)

It could be that Ghash.io is just having extremely shitting blocks

PPLNS is the worst idea in mining ever conceived. Ghash sucks.

Your math is not wrong, its Ghash who is wrong, Ghash is a great representation of a awesome attorney firm, who throws paperwork at the defense. In stressful situations or close losses they will throw as many numbers and statistics at us in hopes we will overlook the true facts,as you can see both your numbers and my numbers are added correctly, yet my account was still only paid 50% of the reward in question.

EDIT:
And now their latest reply to the situation that I have given stats, reports, screenshots and everything else they need

Looks like my math was wrong, my bad there.

No not shill I just mine there with Ant S3s so I see the blocks also. Lots of people quick to attack GHash so I like to defend as my experience there is good

You're absolutely correct, she/he is a shill. Check her/his history out. Ghash/cex have many of them on this forum, it's sad.

I am not sure what makes you think my miner is unstable the picture clearly gives a <5s> average of 1020 and a overall (which would have been a 4 hour average) of 1022. As I had followed their instructions and found out NO it was not my connection or my miner as the other pools I used to test its hash on were matching within the +-10% average it should. I had only 5120 rejects and 21 hardware errors in 3.2 million processed shares, Nothing unstable about that figure is there?

SO it was not my connection or hardware. As you can see in the picture the rate my miner stats have are well under 50% of what Ghash was reporting at the time of that screenshot. it was at only 10% of the work he provided the day before for over 6 hours and a lot more blocks. Even their 1 Hour average is 25% less than what it should be. AND as we all found out it was Ghash.io servers/reporting code not our equipment, as even their script servers were having major issues, it got so bad all external connections were broken leaving only 13Phash for a little while. So this was not an error on my end.

That small window of blocks about the cloud fees was not actually pulled to complain about the payouts, it was pulled to show we were not paid for the blocks that were missing, which as you mentioned have now been paid. But then as I re-read the post I looked closer at the section I had posted, and saw the problems and edited to point the losses out. The bottom line here is it really doesnt matter what you feel the overall situation is you should never lose money on hash you paid a pool for due to maintenance fees, you say their costs go up, how do you think I feel about the 1028 Ghash I was feeding them for 6 hours and only got paid for 10% of that? how am I supposed to feel? Is the electric company going to give me a 90% discount for those 6 hours because Ghash had server or coding or software reporting problems, No, but as you see they gladly took thier fees from the cloud I used to own didnt they?

My miner is stable and happily mining another pool that has reported 1020 to 1058 of hasing power for the past 32 hours actually, Now low payments or exccuses. Thank you very much. I sold their cloud back to them as it is not profitable.

Bottom line Ghash is making themselves rich from its members, fees on withdraws, fees on buying, fees on selling,  fees on cloud for maintenance, fees for farting and burping, fees fees fees, low payouts, and hiding blocks for as long as they can, paying its hardware miners only 50%of their reward. Its just not right and people need informed.

Oh and you must work for Ghash because your math is 50% off in ghash favor

But here are the hardcore facts in the balance statements of each line

0.00026826 <---------ENDING BALANCE
0.00031822  
0.00029059  
0.00030135  
0.00027158  
0.00027365        
0.00024244        
0.00028616  
0.00025517      
0.00028702  
0.00024341  
0.00026737  
0.00022149    
0.00024004    
0.00019416  
0.00024671    
0.00020549  
0.00021815 <--------STARTING BALANCE

So  
 0.00026826
-0.00021815
-------------
 0.00005011

far cry from the 0.00009000 you show in your math. WHICH is actually mathematically correct,however my account was not paid the 0.00009000 Satoshi that the rewards minus the costs show, it was credited only about what? that right folks again the I was credited close to only 50% what it should have been. Another 50% payout average this thread was started about. So thank you employee of Ghash thank you for allowing us to point out yet another way Ghash seems to be taking another 50%

Paying all blocks are important, but is a small issue. These two unpaid blocks are just the one found out by user.

Another problem - not necessarily is cheating but need to be evaluated too.

Cex.io miners shared ghash.io pool with many other, unknown miners. With more non-cex miners are added to pool, the income of cex miners get into 'negative' value with the maintenance fee. Basically being robbed by fellows in the pool.

Non-cex miners in ghash.io got zero % fee.

After the fiasco yesterday, total ghash.io hash rate has dropped suddenly and income of cex.io miners has recovered but how long? Will someone add back the 10PHs and then income get back to negatives again? I think it will come back to 56Phs again.

All I can see from your stats is you have a very unstable miner with huge variance in it's hashing power so something is up with it or your connection with Ghash that is specific to you (hence no one else jumping in with same story). My miners hashing stable over the same period reported by my miners and GHash stats.

Your cloud mining stats, you have picked a small window of 10 hours during which period the block-find times were very very long , 4 hours (x1). 2 hours (x3), 1 hour (x2), less than hour (x3). Even though you highlight 3 blocks where your cost was higher than reward (the long blocks) if you tally all the blocks shown and total reward V's cost you actually still made money in that very bad luck period. Perhaps my math is wrong I just quickly looked and added up what was shown on the screen in a spreadsheet profit 0.00009. Not much admittedly.


It is known fact that the CEX.IO cost for cloud impacts higher on longer blocks sometimes into negative. As difficulty increases that gets a bigger issue. The offset is the high number of block-finds the pool gets of smaller time-frame to balance out the longer ones over time.

So you made some money cloud-mining in a 10 hour period of the worst luck probably ever seen, and 2 blocks that didn't get paid due to an issue at GHash were investigated and have now been paid too. Hopefully your miner is stable and happily hashing again.

I noticed in the customer support tickets you guys seem to do the same thing, you skim past a lot of the information in the ticket and pick and choose what you want to respond to, why have you not addressed the situation and all the proof I posted above, the screenshots, the factual documented payouts and shares provided by workers, as well as the maintenance fees on your cloud that are sometimes larger than the reward on your cloud? You seem to be doing the same exact thing in my support tickets, just skimming past the important things, not even looking at provided screenshots and answering things that are not needed but ignoring the real issues. Thenn closing the ticket claiming it to be merged with others without resolving all the issues in each ticket. responding to a ticket does not mean it is solved, resolving the ticket in hopes that each side is pleased with the outcome resolves a ticket.

Ghash remember you can not plausibly deny simple elementary mathematics, the proof is above. You cant have your cake and eat it to, if 50ghash of cloud that you charge maintenance fees for can process 166,000 shares theh its logically and mathematically correct to understand 1000 Ghash of mining power can process 3.2 million facts are facts. Paying only 1.5 million is in FACT less than 50% of the payout.

To fully come out and answer the OPs question, At this point in time as a (somewhat former) member of Ghash.io I feel YES they are in fact cheating their miners and members and YES they are in fact paying Less than 50% of expected, the proof is in the long post above.

The outstanding issue regarding blocks 327321 and 317304 has been resolved and rewards distributed. Many thanks for your patience.

https://support.cex.io/hc/en-us/articles/203393233-25-August-2014-Missing-Block-Rewards

I know the hashrate on one of my S1's has been all over the place the last few days. We've had server bouncing and some other crap. I had an S1 hashing at 70 GH/s today, the unit showed 187 GH/s.

Even my ghash was low! I have 105 and it was reporting in the 40s.

Yeah the edits kinda confirmed that.  You almost seem mad that someone dared to investigate this.  I thought it relevant to post that I had not seen any others showing it was a one-off thing and not a pattern of behavior. 

I may be wrong, you may not be mad over the fact that someone looked into this and questioned whether cex was living up to its promises.  At least now you can point to a 3rd party and say "even though he reported security problems with our site and we refused to fix them for multiple weeks and they still remain unresolved he did confirm that we pay for every block mined".  Course I still have yet to investigate the smaller payments on those blocks, the original issue of this thread.

The two missing blocks were paid this morning making it a non-issue.


The smaller payouts issue still appears to exist (I have noticed it too I just dont know why).  I do not think this is variance because it may take longer to solve a block but when its solved I am still X% of the pool so I should get X% of the payout.  TXFEEs are so small on a pool that size they do not amount to much of anything.  Additionally the pool shrunk, so presumably my contributions would be a slightly larger percentage of the whole.


Discus fish (f2pool.com) has grown and appears to be larger than CEX.  As of last night (dunno about right now) 40% of the entire CEX pool has left and 50% of external miners left.  Based on figures obtained when their stratum servers died yesterday CEX has 13 PH/s in cloud mining, everything else is external miners.  This is probably for the best given the known security vulnerabilities on the site, the broken code, the constant stream of excuses about how it will take a week to fix problems they just introduced by "upgrading" code without testing it first, the repeated problems of what appears to be their hot wallet running dry.  The 62% (and rising) maintenance fee is going to kill whomever keeps their cloud mining product especially since you cant get rid of it without selling it to someone else.  Someone is going to be left holding the bag on that one.

well it took me a total of 3 minutes to confirm and find the blocks that were processed, and compare the results to my paid blocks and see I was not paid, but it has been well over 9 hours and we still have not been rewarded. So i guess they are taking the "bold" approach here.

EDIT: they have paid for the two blocks, Luckily I made a profit since they were mined with the cloud and have recently been incurring HUGE maintenance fees. PHEW

I believe it was a mistake like you say, it would be pretty bold for an operation as large as CEX.io to think they could hide 2 found blocks worth 25,000.

First let me tell you how i found this out, I had a problem where for 6 hours my miner was getting paid for only 10% of his hashrate, the support team has still made it like it was on my end, during this time their own servers were going up and down, my miner would not failover to another pool because in my cgminer it was connected and hashing,thus a failover would not happen, During this problem I pointed my miner in other places for a test like they asked me to and finally pointed it back to ghash.io and mined a whole 4 hour block.

I then noticed my 50ghash/s cloud I have with them was charged a maintenance fee for 177,624 shares mined that block

I will list a few things for you to determine yourself, along with screenshots to back it up.

My miner report for that block
(5s):1.023T (avg):1.022Th/s | A:3322712 R:5120 HW:22 WU:13.6/m

This was the payout report
17732 2014-08-24 09:49:25 317250 25.0550 1/120 4 hours 46.77 Ph Your shares 1523536/75000007950 0.00% 168878284227 0.00050896

Here is the report from the block cloud mined and its fees.
2014-08-24 18:34:54 0.00050896 BTC   0.00050977   MINING-Block #317250, Reward: 0.00050896
2014-08-24 18:34:54-0.00010196 BTC   0.00040781   MAINTENANCE-Shares 177624 , Cost: -0.00010196

Now if we do a simple mathematical equation it will tell us something interesting

If you can mine 177,624 shares with 50ghash/s of mining power in a 4 hour block, how many shares can you mine with 1000Ghash/s of mining power in a 4 hour block?

Solution 177,624(20) = 3552480

Wow how ironic to see that mathematically the numbers match very closely to what my miner stats output was huh?



So from this we can clearly assume Ghash.io is paying us less than 50% of what we mine, and make many excuses and avoid this situation in customer support. his first response was



Please view the same picture submitted to him NOTICE the pool I am mining in HAHAHAHA.  Also, understand I already told him I had not subtracted the rejected shares from the 3+millions shares provided but even if I did it would still leave my shares provided at over 3 million.

Your thoughts??


In addition lookat the reward versus the cost of their cloud, below is a report of cloud GHS I ussed to own on CEX.io until I saw it was costing me money instead of making me money

2014-08-25 10:19:37   -0.00004996 BTC   0.00026826   MAINTENANCE   -   Shares 87032 , Cost: -0.00004996<-------------
2014-08-25 10:19:37    0.00002763 BTC   0.00031822    MINING   -   Block #317346, Reward: 0.00002763<-----------------LOSS of 0.00002233
2014-08-25 08:18:26   -0.00001076 BTC   0.00029059   MAINTENANCE   -   Shares 18744 , Cost: -0.00001076
2014-08-25 08:18:26    0.00002977 BTC   0.00030135    MINING   -   Block #317335, Reward: 0.00002977
2014-08-25 07:54:04   -0.00000207 BTC   0.00027158   MAINTENANCE   -   Shares 3600 , Cost: -0.00000207
2014-08-25 07:54:04    0.00003121 BTC   0.00027365    MINING   -   Block #317333, Reward: 0.00003121
2014-08-25 07:46:58   -0.00004372 BTC   0.00024244   MAINTENANCE   -   Shares 76152 , Cost: -0.00004372<--------------
2014-08-25 07:46:58    0.00003099 BTC   0.00028616    MINING   -   Block #317332, Reward: 0.00003099<------------------LOSS of 0.00001273
2014-08-25 06:03:07   -0.00003185 BTC   0.00025517   MAINTENANCE   -   Shares 55472 , Cost: -0.00003185
2014-08-25 06:03:07    0.00004361 BTC   0.00028702    MINING   -   Block #317324, Reward: 0.00004361
2014-08-25 04:46:45   -0.00002396 BTC   0.00024341    MAINTENANCE   -   Shares 41736 , Cost: -0.00002396
2014-08-25 04:46:45    0.00004588 BTC   0.00026737    MINING   -   Block #317314, Reward: 0.00004588
2014-08-25 03:48:34   -0.00001855 BTC   0.00022149    MAINTENANCE   -   Shares 32304 , Cost: -0.00001855
2014-08-25 03:48:34    0.00004588 BTC   0.00024004    MINING   -   Block #317314, Reward: 0.00004588
2014-08-25 03:03:57   -0.00005255 BTC   0.00019416    MAINTENANCE   -   Shares 91544 , Cost: -0.00005255<---------------
2014-08-25 03:03:57    0.00004122 BTC   0.00024671    MINING   -   Block #317310, Reward: 0.00004122<-------------------LOSS of 0.00001600
2014-08-25 00:59:13   -0.00001266 BTC   0.00020549    MAINTENANCE   -   Shares 22048 , Cost: -0.00001266
2014-08-25 00:59:13    0.00003989 BTC   0.00021815    MINING   -   Block #317298, Reward: 0.00003989

So ghash.io wheres the block payment for 317304 and block 317321

Recent blocks Found By GHash.IO
Height   Time   Hash
317398 (Main Chain)   2014-08-25 11:01:28   000000000000000005537de7c2e1cff923f24394c7778a4007c90ba7daf667c8
317391 (Main Chain)   2014-08-25 10:27:36   0000000000000000079874d433e7809a3fd707821eae25af7c7b954524a01cd2
317388 (Main Chain)   2014-08-25 09:37:07   00000000000000001b295c20166ff208e6cbb45317bc1c0046c1b496fba11de8
317379 (Main Chain)   2014-08-25 07:21:48   00000000000000000df30b837fa0eb04d0e17ae91f6da42016e251c44570591a
317373 (Main Chain)   2014-08-25 06:11:20   00000000000000000a786f9dce8d4914ab728de70dd5d9958283f8469ccc6f5e
317354 (Main Chain)   2014-08-25 02:38:29   00000000000000000eba653188a2a5e56a327776ce8b50e2fc973cb9f00c82d6
317346 (Main Chain)   2014-08-25 01:21:07   00000000000000000ba156235ee5023a94341ab56261ffb8ea1d82be4d6d9727
317335 (Main Chain)   2014-08-24 23:19:35   000000000000000011138abc2b473e66674a0477a6a2746a7dcec899b9816f44
317333 (Main Chain)   2014-08-24 23:00:00   0000000000000000033869804030d3b792bf05266341e8942d2c7914b4079474
317332 (Main Chain)   2014-08-24 22:36:05   000000000000000026eef432722080188ba9e6a7cde26958562fd17a8bf94089
317324 (Main Chain)   2014-08-24 20:46:04   0000000000000000035c9c33100333fb82b0e81e9445b1289abcde3eee093e53
317321 (Main Chain)   2014-08-24 19:50:55   000000000000000002aa1f3f86b321c00ad0998e2b4c80a0d7b1c21b42e162dd
317314 (Main Chain)   2014-08-24 18:59:04   0000000000000000089e428ee009e7ab7fcf405e6346e1a38c11fd1f15f8a3b9
317310 (Main Chain)   2014-08-24 17:54:49   000000000000000028dd8105985932dc177198bbbcb22da939a5e2c1f180e878
317304 (Main Chain)   2014-08-24 16:47:01   0000000000000000264613cfeb8bade08f5eead26966f568c9fd6ef32dc44616


So exactly what more is there for you to investigate??

EDIT: Actually Ghash.io pls stop farther investigation, After looking at my payout reports closer I think i will be happy with the positive 11,000 satoshi I left in the account before I pointed my hardware elsewhere and sold all my CEX.io GHS in there, and withdrew all myb BTC I had. If you investigate those blocks I will probably end up with a negative balance due to maintenance fees. So I am ok you can greedily keep that 50 BTC  if you need it so darn badly.

GHash.IO pays every found block to its miners, so your investigation regardless of the number of edits will not reveal anything other than that.

We are aware of a discrepancy relating to 2 recent blocks and have announced we are investigating such on our Official thread. https://bitcointalksearch.org/topic/m.8522350

Look at block 317304 and block 317321.  According to blockchain.info it was solved by ghash.io, according to ghash.io they did not solve it so they aren't paying miners for it.  Those are the only 2 out of the last 100 blocks as I only just checked because someone else noticed it first.  

It could be just 2 blocks that they kept for themselves either because their software is broken (again) or because they needed an extra ~$25k for hookers and blow.  I really dont know but it does make me want to dig deeper into which blocks they have paid on and which ones they should have paid on.  If it is 2% of all blocks then there is a serious problem in not disclosing that to people, if they are going to charge a fee they need to declare it and not claim 0% pool fee.


Edit: ha! beat me to it
Edit 2: I am currently pulling blocks from blockchain.info associated with ghash.io to see what is going on.  I will also look at what IPs were used to see if one is particularly bad about it or not.  I am going to go back a couple hundred more blocks and if I dont see anything give up.  Program is running now to do all this.

Edit 3: in the last 167 blocks solved by ghash/cex pool only those 2 did not get paid out.  They still have not been at the time of this writing.

Blocks 317321 and 317304 were found by Ghash.io according to blockchain and not orphaned.

Those same 2 blocks are not even on the list of blocks found on ghash.io ( completely missing for the list ).

I imagine it is just some glitch as I don't think any big pool like ghash would think they could get away with hiding 2 blocks, eventually someone would spot them.

While I would rarely ever defend ghash I do not see any suspicious pattern.  Please point to a specific time period or block sequence where you think they might have been withholding solves for the pool.

Organofcorti does a lot of block solve analysis and identification of unknown hash power in his weekly reporting. You will find some answers to your questions there. https://bitcointalksearch.org/topic/weekly-pool-and-network-statistics-77000

Mostly by Ghash and DiscusFish.

While I agree you should not make rash decisions and jump out of your pool based on your payout dipping due to variance.  There does seem to be some suspicious patterns occuring.


Now that I see Ghash is also paying out less than expected I have to go "hmmm"...and do more research.

http://www.bitcoincharts.com/
Current network speed (calculated by rate of blocks turned in): 147.9PH

https://www.btcguild.com/index.php?page=pool_stats
BTCGuild reported speed (calculated by rate of shares hashed): 12.0PH

http://blockchain.info/pools
BTCGuild reported share of total network (calculated by rate of blocks turned in): 7%

149.9 * .07 = 10.4PH = 12PH - 1.6PH missing blocks

Now of course this can be explained by bad luck, but on how many pools can this bad luck occur.

Also note that the share of network blocks turned in is 9% for two individual unidentified addresses, and 12% completely unknown to blockchain.info.

Obviously there are private players out there, but are they 21% of the actual hashing capacity?

Last link: http://bitcoin.sipa.be/speed-lin-10k.png

A lot of blocks sure are being turned in now that we're in the last 300 blocks before the difficulty change.

While not to get into a pissing war it is the experienced and veteran posters who keep a lot of the noobs from making massive mistakes.  Bitcoin is a community and the protocol follows the communities wishes.  He's trying to influence the way the community decides to distribute its hash.

This is my 3rd account on the forums - after each major hack I just made a new one (ahh Cosbycoin I miss thee).  While every poster has obvious bias to what they say - perhaps there is a reason some scream on these forums for reasons other than mental instability.

Thanks, I am sure lots of people sleeping safer knowing you have their back. Just an observation, you make too many assumptions and plenty of self importance. Good luck defending the 'noobs' from the 'evil'.

You are correct - my statement was not a question & it did not need answering.

Yes, I have made quite a few statements regarding cex/ghash double spending attacks, price fixing/manipulation, fee pricing deletion/extortion, lack of transparency etc, etc, I do this in an effort to educate noob cex users like yourself about the shady practises of the people you are trusting your coins with, to stop you being ripped off & because I believe that any entity that can be dismantled by the truth, should be. Noob cex users like yourself are particularly vulnerable to their pretty website & false statements, as well as being completely unaware of their history. I was around when they did it & was active in finding out the truth - hardly befitting of the Troll you label me as.

Of course, you can mine with who ever you want, but it is important that noobs are made aware of certain goings on to enable them to make an informed decision as to who to use for mining/trading, who is reputable & who is not. If every noob miner done just a little research before diving head first into the prettiest website under the false assumption that (2nd) biggest is best, I probably wouldn't have to remind anyone, but they don't - so I do 

IYF

Why would they again comment on the same old troll post for that is what it is. IFYTech doesn't want an answer he just wants to post the same comments over and over.

IYFTech is also correct - strange how you don't comment on that eh?......

DrG is correct, variance is what you are seeing. When you tally your daily returns also look at the number of blocks solved in that same period and track that. Then you will we the impact of longer block times from difficulty / luck issues.

Ghash.io is one shady site by my option, i never mined there as i've seen alot of posts about them...you better mine on other pool.

Could not say any better.

Thank you!

Ghash has been cheating miners in various ways since day one, period. Their price manipulation is legendary, as is their fee changes without notice after deleting their prices from their own blog.

Then there's the small matter of double spending against the Bitcoin network by them, which they lied about. They're not just cheating miners - they're guilty of cheating the whole Bitcoin network.

Avoid them like the plague.

It's called variance, and you cannot escape it - no matter which pool you run to.

Ghash has had bad luck for the last 2-3 days (look at the 3 and 4 hour blocks).  On top of that the network speed has grown but ghash hasn't, so it's share of the network went down.

No pool is able to avoid variance.  Use CGminer to load balance your shares across multiple pools and decrease your variance further.

I've been mining on ghash.io since i sold off my ghs from cex.io to buy into my own asic hardware. At about 1.8 TH/s i've been pulling down about .034 to .036 or so per day. You said "best conditions" and by your numbers i should be getting 0.048312 per day. So if i assume NOT "best conditions" then should i think .036 instead of 0.048312 is reasonable?

also, something that might affect it - i've been mining on cex/ghash for about 8 months, and plotting/graphing the entirety of it for analysis purposes. The thing that i have found to be very intriguing is that when the difficulty changes, it really doesn't seem to have much affect on my mining production. like literally at all. with a slow decay in production over time, it's almost as though they linearize the decay that happens due to difficulty drop, and by that i mean make it into a constant decay rather than a stepped change like difficulty by adjusting based on the expected difficulty change which is amazingly accurate, especially the closer it gets to the actual diff change. my theory is that this is how they make their profit since they have a 0% pool fee. and honestly, i kinda like it... i'm ok with them making their profit in an innovative way outside the box of what everyone would normally assume.

if this is true, then it means what you should be getting vs. what you are actually getting would be different immediately before and immediately after a diff change.

whether i could and/or should be getting that extra 0.012312 per day, well, i have to do some analysis on that. when i'm not focused on building out my mining op i'll spend some time deciding whether to go to another pool and which one. but i like the fact that ghash is tied to cex, and the reason i got into cex was not specifically for the cloud mining but rather the commodity trading of ghs. regardless of the fact that their ghs is more expensive than hardware, regardless of how much i had, i was able to nearly double and quadruple it by seizing lucrative trading opportunities. because of that i was able to make thousands of $USD worth of bitcoin in profit, and sell out to by 20 s3's this week.

thank you single post troll.. this is a new level.. i wont be pm'ing you but thanks for the advice.  i hope you send some btc to ghash soon before they take it out of your bank.. you still owe them 0.00002 per block you helped mine.

I've strayed away from them quickly... Its not even worth it to keep my systems hooked to them.  I Decided to go to another pool that works just as well but a little better.

The fact you've been making almost 50% of what you should is already a red flag.    I was using them for my systems and I was getting 40% roughly   then I put a few hundred GH/s into their cloud and was getting more taken away in fee's than I was recieving (i.e like I would get 0.0001 from a block and the fee's would have been 0.00012) so I was losing quickly.... if you want a site to try... PM me

issues with ghash?
anyone experiencing the same as well or am i totally wrong?

example.. 1 TH mining power i should be earning 0.02684 daily according to bitcoinwisdom with best conditions at current diff.  
past 3-4 days or so i'm making less than 0.012 per th.

previously when ghash was mining every 3rd or 4th block i would get close to expectations -20% to -25%

1) is this acceptable?  
2) if the total hash rate of ghash has dropped and my hashrate remains the same per block found, i should not have my overall earnings affected over time?

is my logic correct? where am i mistaken?
i have checked my miners and they are hashing at normal speed.